Dictionary of Ichthyology

Brian W. Coad and Don E. McAllister^†

Revised: 26 May 2008

A

A = abbreviation for acre.

A = abbreviation for anal fin (rays).

A = annual total mortality rate (the number of fish which die during a year divided by the initial number. Also called actual mortality rate, coefficient of mortality (Ricker, 1975)).

a or a = abbreviation for annum, meaning year. Usually used in combination, e.g. Ma, meaning million years.

A1 = abbreviation for first anal fin (rays).

A2 = abbreviation for second anal fin (rays).

A30 = number of anal fin rays anterior to the 31st vertebra, e.g. in Carapidae.

A100 = number of anal fin rays anterior to the 201st vertebra, e.g. in Nemichthyidae.

a posteriori classification = a classification made based on the results of experimentation.

a priori classification = a classification made prior to experimentation.

a- (prefix) = lacking, absence of, not, without; but see below, a-fishing.

A-B direction = in net making, the direction parallel to a rectilinear sequence of mesh bars, each from adjacent meshes.

a-fishing = in the act or process of fishing; gone fishing.

A-ft = acre-foot (one acre of surface covered with 1 foot of water (1,233,500 L, 1233.5 m³, 325,850 gal).

A-grade = a freshness grade for fish used in the European community.

a.k.a. = also known as.

aav(e) = the small round net by which boys pick up herrings that fall from the nets as these are being hauled in (Scottish dialect).

ab- (prefix) = from, away from.

abaxial = at a point away from, or distant from, the axis.

abbreviate heterocercal = type of caudal fin in which the vertebral column extends only a short way into the upper lobe of the fin (which is longer than the lower lobe); a heterocercal caudal fin approaching the homocercal type, e.g. Lepisosteidae, Amiidae.

abbreviation = a shortened form of a word or title. In zoological works genus-group names cited in binomial names of species are often abbreviated to one or two letters for convenience, e.g. Salmo trutta may be abbreviated to S. trutta, the abbreviation always being followed by a full stop (or period). The abbreviation should not be used on the first mention of a name. Similarly specific names cited in trinomial names of subspecies may be abbreviated.

ABC = allowable biological catch (a term used by a management agency which refers to the range of allowable catch for a species or species group. It is set each year by a scientific group created by the management agency and is the subjectively estimated amount of catch of a given species from a given region. The agency then takes the ABC estimate and sets the annual total allowable catch (TAC)).

abdomen = 1) the part of the body containing the viscera (intestine, liver, kidney, reproductive organs, etc).

abdomen = 2) the lower part of the body of fish, the belly.

abdominal = pertaining to the abdomen. Pelvic fins are said to be abdominal when they lie behind the posterior tip of normally developed pectoral fins.

abdominal cavity = the part of the body containing the viscera or guts, liver, ovaries, testes, kidneys, etc.

abdominal dropsy = oedema, an accumulation of excess fluid in the abdomen, causing abdominal swelling and marked protrusion of scales. Also called pinecone disease, q.v.

abdominal fishes = those bony fishes having pelvic fins in the abdominal position.

abdominal pore = an external aperture near the vent communicating with the abdominal cavity. Found in Cyclostomata, Elasmobranchii, and in some Teleostomi, e.g. Salmonidae.

abdominal ridge = paired dermal ridges running from pectoral to pelvic fin bases in sharks.

abdominal serra = an abdominal spine, formed from a scale in the ventral region of the fish body. A series of these serrae form a saw-like edge and their numbers can be used in identification of some Clupeidae and Serrasalmidae.

abdominal vertebra = one of the anterior vertebrae bearing ribs but lacking the haemal arch, canal and spine of caudal vertebrae, q.v.

abducens nerve = cranial nerve VI, innervating the lateral rectus eye muscle which rotates the eyeball laterally and the retractor bulbi muscles in part. See cranial nerves.

abductor = a muscle that draws a part away from the axis of the body, or separates two parts.

Aberdeen cut = a cut of fish from a frozen block, rhombus-shaped with the sides often squared off or cut with a tapered edge. Usually breaded and battered. Also called diamond cut and French cut.

Aberdeen hook = a hook shape characterised by a slightly-squared round bend and a wide gape used for baiting with minnows

aberration = 1) a term used to denote a class of individuals within a species. A name which explicitly refers to an aberration unequivocally treated as an infrasubspecific entity is unavailable.

aberration = 2) an aberrant fish, deviating from the usual or natural type in colour, form, behaviour, etc.

abioseston = non-living components of the seston, q.v.

abio- = without a living, starving.

abiotic = referring to non-living structures, substances, factors, environments, etc.

abnormal = not normal; contrary to the usual structure, position, behavior or rule.

abnormal host = accidental host.

abnormality = any condition not found naturally in most fishes. Unusual conditions arising during processing fish as food are called defects, q.v.

aboral = opposite or away from the oral or mouth area/cavity. May be used in the sense of opposite to a biting tooth surface where this aboral end of a tooth is not a root, e.g. tooth plates in Chimaeriformes and pavement teeth, q.v., in some rays, skates and sharks.

abortive = remaining or becoming imperfect.

abraded = worn or frayed, e.g. fins of fish after spawning.

Abramis brama = 1) the common bream, a cyprinid found from the British Isles across Europe north of the Pyrenees and Alps eastwards to the Black, Caspian and Aral sea basins.

Abramis brama = 2) a Swedish rock band that even a had an album with a line drawing of the fish on it.

absolute abundance = the total number of a kind of fish in the population. Usually estimated from relative abundance as it is rarely known.

absolute conversion rate of food = an index calculated by dividing the quantity of food distributed by the extra growth believed to have been obtained only from that food.

absolute fecundity = total number of eggs in a female.

absolute growth rate = the actual increase in size of an individual, stock or population over a given time span and under specified conditions.

absolute recruitment = the number of fish which grow into the catchable size range in a unit of time (usually a year)(Ricker, 1975).

absolute synonym = homotypic synonym (a synonym based on the same nomenclatural type).

absolute tautonymy = the identical spelling of a generic or subgeneric name and the specific or subspecific name of one of its originally included nominal species or subspecies.

absolute tautonymy = the identical spelling of a generic and species or subspecies name originally included in the genus.

absorptive feeding = nutrient acquisition during fish ontogeny from an ovarian secretion via flaps, trophotaenia, or trophonemeta, or from the environment via body surfaces or special external gut and finfold structures.

abundance = degree of plentifulness. The total number of fish in a population, stock, other group or on a fishing ground. Can be measured in absolute or relative terms and may be number per area or per unit fishing effort.

abundance index = data obtained from samples or observations and used as a measure of the weight or number of fish which make up a stock, a segment of a stock such as spawners or in a given area. Most indices are relative units (as opposed to measuring absolute abundance), and simply indicate relative changes in abundance over time. The data is obtained from scientific surveys or inferred from fisheries data.

abyss = water below 4000 metres or 2000 fathoms (= 3660 metres), down to 6000 metres, where light does not penetrate. Occasionally used for depths below 2000 metres. A constant environment with temperatures usually 0-2°C or temperatures are uniform. From the Sumerian abzu, meaning primordial sea.

abyssal = adjective for abyss.

abyssal benthic = pertaining to the ocean floor below 400-600 fathoms (730-1100 metres).

abyssal depth = see abyssal for oceans; in fresh water it may mean the maximum depth or the depth at which water temperature remains uniform.

abyssal floor = abyssal plain.

abyssal plain = the area of the generally flat ocean floor excluding ocean trenches below 2000 fathoms (3660 metres, presumably an older version based on fathoms) or 4000 metres.

abyssal zone = the middle zone of the deep sea between 3700 and 6000 metres.

abyss- (prefix) = bottomless.

abyssalpelagic zone = the abyssopelagic area of the ocean.

abyssobenthic = the depth zone of the ocean floor between 4000 and 6000 metres, or from about 3700 m downward, or below the 4°C isotherm.

abyssopelagic = living in the water column at 4000 to 6000 metres (or 2500-4000 metres, or 4000-7000 metres, sources differ), seaward of the continental shelf-slope break. See also abyssalpelagic zone.

AC = a series of ventro-lateral photophores extending between a vertical at the anal fin origin and the end on the caudal peduncle. The AC row may begin posterior to the anal fin origin if it is offset from other ventro-lateral photophores.

ac = abbreviation for acre.

ac ft = acre-foot.

acantho- = a prefix meaning with spines.

acanthotrich = a spiny dorsal or anal fin ray.

acanthotrichia = plural of acanthotrichium.

acanthotrichium (plural acanthotrichia) = acanthotrich.

acanthostedion = postlarval stage of the Peristediidae characterized by long parietal spines and development of rostral exsertions.

acaudal = lacking a tail.

acceptable biological catch = subjectively estimated amount of catch of a given species from a given region. The sustainable harvest used to set the upper limit of the range of potential annual total allowable catch. Also called allowable biological catch.

acceptable catch estimate = an approximate estimate of the catch of a given species that could be taken from a stock in a given region. Also called allowable catch estimate.

acceptable impact = a negative, or potentially negative, alteration of the fishery resulting from human activities. The impact is acceptable since it represents a low risk to the resource. As it is under continuous review, it may be revoked.

accepted name = a name adopted by an author as the correct name for a taxon where names are in dispute.

access = 1) the means by which a person enters a water body, usually with a boat.

access = 2) access right.

access right = the authorisation given to a user, e.g. a vessel owner, by a fishery management authority or by legislation, to exploit a resource, a particular species, or a share of a total allowable catch. Access rights may be free of charge or require payment and are usually conditional and used under constraints specified in a management plan.

accessibility = the condition of fish occupying a locality where they can be caught using the appropriate gear.

accession = 1) the formal acceptance into museum custody of a specimen or a collection of fishes, and the recording of such.

accession = 2) a specimen(s) acquired by a museum for its permanent collection.

accession = 3) the act of recording and processing an addition to a permanent collection.

accession list = a document in which accessions are recorded, usually chronologically by date of receipt; may be a bound volume and/or a computer file.

accession number = a unique number assigned to an accession, usually sequentially in chronological order of receipt.

accessioning = accepting legally a fish collection, containing one to many specimens and species, with date of receipt, ownership, donor, etc.

accessory breathing organ = labyrinth organ (a much folded suprabranchial accessory breathing organ found in Anabantoidei. Formed by vascularized expansion of the epibranchial of the first gill arch. Used for respiration in air).

accessory caudal ray = one of a series of short, procurrent rays on the upper and lower margins of the of the caudal peduncle.

accessory dorsal branch = a lateral line branch found in some flatfishes, running from the head for varying lengths below the base of the dorsal fin.

accessory growth centre = a growth centre outside the core of the fish otolith from which new growth may occur. May result from metamorphosis. Also incorrectly called accessory primordia.

accessory lateral line = accessory dorsal branch.

accessory male = a male fish which attempts to fertilise eggs of a breeding female at the expense of a dominant male.

accessory olfactory sac = olfactory ventilation sac (an extension of the olfactory cavity, often characteristic of inactive bottom dwellers living in still water such as flatfishes, dipnoans, and eels but also found in clupeids, salmonids, mugilids and scombrids. Primarily used for ventilation but also produce mucus. There may be up to four sacs, usually the additional sacs are smaller but in Osmeridae the sole accessory sac is larger than the main sac).

accessory pectoral scale = accessory scale.

accessory pelvic appendage = a tapered fleshy lobe above the base of the pelvic fin. May be covered by a scale.

accessory primordium = an additional growth centre outside the otolith core but lacking primordial granules. Accessory growth centre is preferred.

accessory respiratory organ = a superficial or internal organ which complements the gills in exchange of gases with the environment when the fish is in poorly oxygenated water or in air. In some cases it may also function as a hydrostatic organ.

accessory scale = axillary scale (a small triangular appendage or a modified scale at the upper or anterior base of a paired fin. Also called fleshy appendage and inguinal process. Functions apparently to streamline the fin when held against the body while swimming).

accidental catch = other fishes caught during a fishery directed to a target species. The fish may be taking bait meant for other fish, chasing the target species or are swept up by the gear used. Also called incidental catch or by-catch.

accidental host = a fish serving as a host for a variable length of time for a parasite of another animal. Also called abnormal host.

accidental parasite = a parasite which has infected an unusual host.

accidental species = normally marine species occasionally found in fresh waters but not in any regular or predictable manner. Records are usually few.

acclimation = the process by which fish become used to new circumstances. Often used in adjusting to changes in temperature, water quality, lighting regimes, being netted, etc. in aquaculture or aquaria. Fish may be more susceptible to pathogens and eat poorly while acclimating.

acclimation pond = a pond or temporary structure used for rearing juvenile fish, acclimating them to specific conditions and, for migratory fish, imprinting the water of a particular stream.

acclimatisation = adaptation to a new environment by a population by selection.

Acclimatisation Society = an organisation in Australia in the mid-nineteenth century set up to introduce familiar European species, e.g. roach, Rutilus rutilus, a cyprinid.

acclivous = having a gentle upward slope.

accommodation = changing the focus of the eye; in fishes the lens moves back and forth in relation to the retina like a camera.

acentrous = without vertebral centra, with persistent notochord, e.g. Dipnoi, Holocephali.

acequia = an irrigation ditch or canal, often community run (southwest United States).

acetic acid = an organic acid, CH₃COOH, used in diluted form in preparation of fish marinades, q.v.

achondral bone = dermal bone (any of the superficial bones in Teleostomi derived from the dermis and overlying the deeper elements of the skull. Primitive fishes have more dermal bones than higher ones, e.g. the armour of Ostracodermi. Dermal bones are a form of membrane bones, i.e. they arose directly from connective tissue membranes without the cartilaginous precursors which precede endochondral bones. They may be divided into laterosensory canal bones that develop in relation to the sensory canals, bones derived from mesenchymous tissue and anamestic bones (q.v.). Also called covering, membrane and investing bones).

achyliasis = an external fungal infection of fishes, genus Achyla.

aciculate = needle-like.

acid curing = marinating or preparing a marinade (a marinade is acidified brine, acetic acid, olive oil or vinegar with or without spices in barrels or special containers in which fish are soaked. The cured fish are packed in mild acidified brine variously with spices, sugar, wine, vegetables and flavourings, e.g. rollmops, Bismarck herring. Salt helps firm the flesh. Chilled marinades have a shelf life of 1-2 months, canned marinades much longer. The pH must not exceed 4.5 as below this spoilage does not occur and food poisoning bacteria do not grow. However some bacteria and enzymes are active and aid ripening, contributing to texture and flavour. Cold marinades are preserved by their acid and salt content, cooked marinades by this and by heat or pasteurisation).

acid death point = the pH at which fish die from acidity of water, usually about pH 4.0.

acid deposition = the addition of acidic material to the ground or water, usually from sulphur and nitrogen compounds emitted by factories and deposited far from this source. Wet deposition is also called acid rain, q.v., and is the result of rain, snow or fog while dry deposition results from particle fallout or acidic gases.

acid detergent fibre = the carbohydrates in an aquaculture feed that are not solubilised by acid detergent. This plant material is not easily used by fish. Abbreviated as ADF.

acid lake = any lake with a pH less than 6.0.

acid neutralising capacity = the property of water that reacts with an acid; formerly alkalinity. Abbreviated as ANC.

acid pickle = an acid solution for curing or marinating fish.

acid rain = rain falling through an atmosphere containing sulphur dioxide and nitrogen oxide pollutants thus making the rain acidic (pH less than 7.0); in lakes without the ability to neutralise the acid survival of fish eggs and young is compromised. Also referred to as acid deposition and wet deposition.

acid-cured fish = fish preserved or marinated in acidified brine with or without spices.

acidic stress index = a function of pH, calcium and inorganic monomeric aluminium conditions in natural waters; used in fish toxicity models.

acidity = a measure of the hydrogen ion concentration, a pH less than 7.0, or the quantitative capacity to neutralise a base to a designated pH.

acidophile = fish from acid waters, like the Amazon and forest pools in West Africa, preferring a pH below 7.

acidophilous = having an affinity for or thriving in acidic conditions, e.g. in a bog or marsh. Also called acidophilic.

acidotrophy = waters where the hydrogen ion concentration is high, producing highly acidic reactions, and in which humic material is lacking.

acinaciform = slender sword, of scimitar-like form, e.g. acinaciform branchiostegal rays in Perciformes.

acini = plural of acinus.

acinus (plural acini) = a lobule of a secretory gland formed by a group of exocrine glandular cells, e.g. in the pancreas.

acipenserin = a toxic substance reputedly obtained from the gonads of sturgeon, Acipenser.

acker = the break or movement made by a fish in the water (English dialect).

acmic = referring to periods of seasonal change in an aquatic population.

acoustic = concerned with hearing or sound.

acoustic bait = a device making sounds or vibrations used to attract fish, e.g. shark rattles, q.v., beating the water surface, spraying the water surface with hoses in the tuna line fishery, croakwood, q.v., bells, etc.

acoustic device = 1) an acoustic harassment device.

acoustic device = 2) a pinger (a sound-emitting device. Attached to static nets to discourage dolphins and porpoises from their vicinity so that the mammals do not become entangled).

acoustic fish tag = a transmitter implanted or attached to a fish to monitor fish movement.

acoustic harassment device = an underwater device that generates sounds to deter marine mammal predators from salmon farms.

acoustic survey = a method of gathering information on fish availability and abundance by using echo sounders and sonar.

acoustic tag = a sound transmitter attached to a fish.

acoustico-lateralis system = the sensory system consisting of the lateral line and the inner ear.

acquisition = transfer of title for a specimen(s) to a museum. Acquisitions may be gifts, purchases, bequests, exchanges or the results of field work.

acre = 4046.9 m², 0.405 ha, 43,560 ft², 4840 yd², 0.00156 mi². There are 640 acres in a square mile. The metric version is the hectare, q.v.

acre-foot = one acre of surface covered with 1 foot of water (1,233,500 L, 1233.5 m³, 325,851 gal.). Used to measure volumes of water used or stored, such as in reservoirs. Abbreviated as ac ft or af in the U.S.A.

acrodin = tissue forming a cap on teeth found in ray-finned fishes.

acrodont = type of tooth ankylosed to the jaw along the midline of the jawbone, rather than to the inner edge, the condition in most fishes. Attachment is by connective collagenous tissue with impregnated calcium salts and, in maxillary and mandibular teeth, by a bony piece between the tooth and the bone.

acronurus = postlarval stage of Acanthuridae.

acronym = any abbreviation using the initial letters of the words abbreviated. Museum collections of fishes are catalogued with an acronym and a number; these acronyms are listed in Leviton et al. (1985) and Leviton and Gibbs (1988).

acrosome = a cap over the nucleus of spermatozoan heads having enzymes involved in sperm penetration of the egg and possibly fusion of egg and sperm. Absent in most Teleostei.

acrylic = a plastic material used in aquaria construction and for aquarium accessories such as filters.

act, nomenclatural = a published act which affects the nomenclatural status of a scientific name or the typification of a nominal taxon; available nomenclatural act is one that is published in an available work; invalid nomenclatural act is any nomenclatural act which is not valid under the provisions of the International Code of Zoological Nomenclature; unavailable nomenclatural act is one published in an unavailable work; valid nomenclatural act is one that is accepted under the provisions of the Code, i.e. the earliest available act not contravening any provision of the Code.

actiniariophil = a reproductive guild (q.v.) where adhesive eggs are deposited in a cluster at the base of a sea anemone. Parents guard the eggs and coat them with mucus as protection against nematocysts. Free embryos are phototactic, planktonic and early juveniles select the host anemone, e.g. Amphiprion allardi.

actic = pertaining to rocky shores; between the low and high tides; intertidal; littoral.

actinic = a type of lighting used in aquaria. It provides the blue end of the spectrum for photosynthesis.

actinophore = the pterygiophore(s) and the associated fin ray.

actinost = one of a series of endochondral bones in the pectoral and pelvic girdle on which the fin rays insert. Most teleosts lack or have greatly reduced pelvic actinosts. Teleosts have one row of actinosts between the fin rays and supporting skeleton (coracoid and scapula for the pectoral, basipterygia for the pelvic) while other fishes may have more rows, referred to as radials.

actinotrich = a slender, horny, flexible, unsegmented fibril which strengthens the embryonic fin fold and which may persist in the outer edge of the adult fin membrane or in the adipose fin. It develops intercellularly rather than cellularly. Persists in fins of Elasmobranchii, Holocephali, and sometimes in Teleostomi distal to the lepidotrichia that replace them. Actinotrichia are translucent, exhibit birefringence (double refraction) and are composed of a scleroprotein called elastoidine. They may be homologous with ceratotrichs found in cartilaginous fishes because of their horny or keratinous nature.

actinotrichia = plural of actinotrichium.

actinotrichium (plural actinotrichia) = actinotrich.

action = 1) the performance of a fishing rod while fighting a fish. Measured as the time elapsed between flexion and a return to a straight configuration. Action can be slow (the most flexion, 90% of the rod bends) to fast (30% of the rod bends); also referred to as stiff, parabolic, etc. May also refer to the rod strength, a light rod being limber and a heavy rod stout.

action = 2) the gear of fishing reels.

action = 3) the movement and performance of a fishing lure in the water.

action = 4) when fish are biting.

action = 5) dragging a fishing fly across the current resulting in an unnatural drift.

activated carbon = pure carbon in porous form used in aquaria to adsorb dissolved organic matter, chlorine, and yellowing compounds (and hence in the latter case keeps water clear). Must be changed regularly as it clogs and can release phosphates into the water which promote algal growth.

activated charcoal = activated carbon.

active = fish intent on feeding. Also called positive.

active capture gear = equipment used in active fishing, such as trawls.

active fishing = fishing with gear that is not stationary, e.g. trawls.

activity coefficient = ratio of the metabolic activity of a fish at rest with that at maximum activity.

actomysin = a combination of actin and myosin, the two main proteins in all fish muscles.

actophilous = thriving on rocky shores.

actual mesh size = stretched mesh size of a net as determined by a standard process such as use of a mesh gauge, q.v.

actual mortality rate = annual mortality rate.

aculeate = bearing a sharp point.

aculeiform = needle-shaped, e.g. pipefishes.

acuminate = tapering gradually to a point, e.g. the tail of Anguilliformes.

acute = 1) ending in a sharp point

acute = 2) running a short and intense course as in toxicity or inflammation.

acypriniod zone = those regions lacking Cyprinidae - South America and the tropical Pacific Islands approximately east and south of Wallace's Line including Australia.

A.D. or AD = abbreviation for anno domini, or Year of the Lord, the Christian dating system. Common era or CE is used as a neutral version.

ad hoc = for the specific purpose, case or situation at hand and for no other.

ad int. = ad interim, meaning for the present, provisionally.

ad libitum = to the limit; often meaning fed until satiated.

ad muraenas = ponds for the culture of moray eels were common in Roman times and a punishment for recalcitrant slaves was throwing them in these pools as food for the morays.

ad- (prefix) = to, on the side of.

Adam's special = an artificial dry fly used to imitate an adult mayfly.

adaptation = the process (or its results, e.g. a structure) wherein individuals, populations or species change to cope with their environment or changes in that environment.

adaptive management = a management process involving feedback to test performance and perhaps deliberate intervention to test the fishery system's response.

adaptive radiation = speciation of a taxonomic group to fill numerous previously vacant ecological niches, e.g. Cichlidae in the Great Rift Lakes of Africa, Cottidae in Lake Baikal of Russia.

adaxial = the paraxial mesoderm subregion developing just adjacent to the chorda mesoderm or notochord rudiment.

added-value = processing of fish before export.

addersteean = adderstone.

adderstone = a stone (grey alum shale) with a hole through it, hung on fishing boats as a charm. Old spindle-whorls, reputedly made by adders (an English venomous snake).

adderstyen = adderstone.

additional catch = supplementary catch obtained either on purpose or by accident.

additional material = specimens other than those in the type series; these may be used to describe a new species but have no nomenclatural significance.

additive = any chemical added to fish for stability during storage, prevention of bacterial growth and toxin production, for colour and appearance to consumers, retention of moisture, prevention of off-flavours, etc. Additives include salt and ascorbic acid which are naturally present in foods and also other chemicals whose use is regulated.

adductor (plural adductores) = a muscle that brings one body part towards another.

adductor mandibulae = a muscle of the cheek area which acts to close the mouth and compress the lips. It is divided into four parts in the perch (Perca flavescens): part 1 has its origin on the dorsal half of the vertical arm of the preopercle and inserts at the centre of the maxillo-mandibular ligament (q.v.). It is a large muscle below the eye. A third part of the ligament serves as an origin for the fourth part of the muscle. Part 3 originates on the pterygoid bone and inserts with part 2 on the maxillo-mandibular ligament beneath the insertion of part 1. Part 2 is a large muscle below part 1. Part 4 originates on the internal portion of the maxillo-mandibular ligament and inserts on the ventral, internal part of the dentary and so is on the lower jaw.

adductor operculi = a muscle originating from the pterotic bone posterior and medial to the origin of the elevator operculi and inserting on the dorso-medial surface of the operculum ventral to the insertion of the levator operculi.

adductores = plural of adductor.

adelph- (prefix) = brother.

adelfophagy = feeding on retarded siblings within the uterus, e.g. Lamna nasus, Odontaspis taurus, Latimeria chalumnae, a form of uterine cannibalism. Also spelled adelphophagy.

adelphophagy = adelfophagy.

adeno- (prefix) = gland.

adenohypophysis = part of the pituitary organ of the lower brain involved in hormone control.

adenoid organ = a lymphoid structure in the lining of the oesophagus of Elasmobranchii.

adequate diet = balanced and fully sufficient feed in aquaculture or nature.

ADF = acid detergent fibre.

adfluvial = 1) living in lakes and migrating into streams to spawn; juveniles feed in streams but migrate to lakes as subadults for feeding.

adfluvial = 2) pertaining to flowing water.

adherent = attached (firmly); sticking; connected with. Said of scales that do not detach easily, for example.

adhesion = connective tissue growth within and around an organ causing it to attach to the peritoneal or pericardial walls. Usually results from inflammation or parasite infestation.

adhesive = 1) sticking, as in eggs to the substrate or to other eggs.

adhesive = 2) sticking, as in structures used in attachment by fishes.

adhesive disc = adhesive disk.

adhesive disk = a sucker-like organ for clinging to various surfaces, e.g. the modified pelvic fins in Gobiescoidae and Liparidae, and the dorsal fin in Echeneidae. Also spelt adhesive disc and used for the adhesive organ.

adhesive egg = a fish egg that is deposited on sand, gravel, plants, etc. to which it sticks by means of the egg's sticky surface. In aquaculture situations this is inconvenient and the adhesiveness can be removed by milk or tannin.

adhesive head gland = adhesive organ.

adhesive organ = transient larval organs near the mouth used to attach the larvae to the substrate, e.g.in Protopterus, Lepidosiren, Acipenser, Esox, Macropodus.

adipocyte = a fat cell.

adipose = fat.

adipose clip = removal of the adipose fin in a hatchery-reared fish, indicating that it contains a coded-wire tag, q.v.

adipose eyelid = transparent membrane(s) over the anterior and posterior regions of the eye, e.g. in Scombridae, Clupeidae, Albulidae, Mugilidae. It serves for streamlining and protection and may cover much of the eye except for a small central opening.

adipose fin = a small fleshy fin lacking rays or spines but reinforced by actinotrichs posterior to the soft dorsal fins (rarely a hard ray or a few soft rays may be developed in the adipose fin of certain catfishes), e.g. in Salmonidae, Osmeridae, Argentinidae, Myctophidae, Ictaluridae, Percopsidae.

adjuvant = material added to a vaccine to enhance the immunological response.

admiral = 1) the master of the first English fishing vessel to reach a cove or harbour in Newfoundland, exercising certain privileges for the season.

admiral = 2) the master of an English fishing vessel, chosen weekly to exercise jurisdiction over European fishermen in a Newfoundland harbour.

admiral = 3) the fisherman who is in charge of the herring fleet (Manx).

Admiralty pattern anchor = the standard pattern of anchor, q.v., comprising two flukes (which dug into the sea bed), a shank and stock. In the eighteenth century a collapsible stock was introduced for easier storage.

admissible = the form of a name which can be validly published and the use of a name or epithet in accordance with the provisions of the International Code of Zoological Nomenclature.

adnasal bone = a small dermal bone in front of the nasal bone in some fishes, e.g. the middle bone of three in the nasal region of Lepisosteus. Also called nasal bone.

adnate = closely attached to, joined along whole length without a free tip; conjoined; adhering, e.g. adipose fin in Noturus (Ictaluridae).

adnate eye = an eye joined by a membrane to the orbit.

adnexed = unattached, with a free edge, not united, flag-like e.g. the adipose fin in salmonids. Opposite of adnate.

adopt = to use an unavailable name as the valid name of a taxon in a way which establishes it as a new name with its own authorship and date.

adpressed = pressed flat against the body; appressed.

adrenal gland = absent in fishes but said to be present in sculpins (Cottidae). Interrenal cells associated with major blood vessels in the anterior kidney represent adrenal cortical tissue in fishes. Adrenal medullary cells are associated with sympathetic ganglia in clumps between the anterior kidney and spine or in the interrenal tissues.

adrenalin = a hormone causing the flight or fight behaviour in response to a sudden stress.

adrenaline = adrenalin.

adtidal = living immediately below the low tide level.

adult = a sexually mature animal; a fish that has reached the length or age of first maturity.

adult equivalent population = the number of fish that would have returned to an area, such as an estuary, in the absence of any prior harvest.

adult fish count = a count of adult fishes passing by a fish-viewing window. Such windows can be placed at the upstream end of fish ladders on dams. Observers count the number of fish according to pre-set criteria, e.g. by species and size, for 50 minutes of every hour for 16 hours per day. Extrapolations can then be made for times when fish are not observed. Separate counts can be made for adults and jacks (precocious male salmonids that can be identified by their smaller size).

adult habitat = an area that provides the necessities of life for an adult fish (angling).

adult period = this period begins with the first maturation of gametes and is characterised by spawning, either annually or only once, and by a slowed or arrested growth rate.

adult stock = spawning stock (the mature part of the stock that is able to spawn; the number or biomass of all fish beyond the age or size class in which 50% of the individuals are mature).

adv. = advena, alien, introduced.

advanced = derived (a character or character state not present in the ancestral stock; apomorphic. The term should not be applied to organisms or taxa since they are a mix of plesiomorphic and derived character states).

advanced fry = a larval fish that has absorbed the yolk, correctly postlarva.

advena = alien, introduced. Abbreviated as adv.

adventitious = accidental, occurring at an unusual locality, as in an adventitious visitor.

adventive = an introduced species not yet established in the wild.

adventure = a commercial fishing enterprise. Also called venture.

adventurer = 1) a migratory English fisherman operating seasonally in Newfoundland (archaic).

adventurer = 2) a resident fisherman who fishes seasonally in coastal waters distant from his home port in Newfoundland.

advertisement = bright colours and conspicuous patterns shown by fishes. Used to indicate unpleasant taste, venom, sex and mood (paling when frightened, darkening when sexually excited).

aeration = introduction of air into water.

aerator = 1) an air pump used to oxygenate aquaria.

aerator = 2) a battery-operated pump used to oxygenate water in a bait bucket by anglers.

aerator = 3) a device to oxygenate water in an aquaculture facility.

aerial fishing = the use of aerial traps (q.v.) to catch fish.

aerial redd survey = a method used to estimate numbers of spawners in a river by counting the number of redds visible from an airplane.

aerial stocking = releasing fish into a water body from a plane or helicopter. Usually fry are stocked in this way.

aerial survey = a method of gathering information on fish shoal movement and density by visual observation and photography from low-flying aircraft.

aerial trap = a trap used to take jumping fish, e.g. mullets and flyingfish. Fish are caught on the surface in boxes, rafts, boats and in such nets as veranda nets. The fish may be frightened into jumping out of the water.

aero- (prefix) = air.

aerobi- (prefix) = living in air.

aerobic pond = a shallow pond, 0.3 m deep, in which photosynthesis is at a maximum, aerobic conditions are maintained and wastes are processed by microorganisms.

aerofoil = modified pectoral and pelvic fins used for gliding.

aerophil = 1) a reproductive guild (q.v.) of a terrestrial spawner characterised by small adhesive eggs scattered over damp sod, by not being photophobic and having moderately developed respiratory networks, e.g. Brycon petrosus.

aerophil = 2) a reproductive guild (q.v.) of a terrestrial spawner where adhesive eggs are tended after deposition on the underside of structures above the water surface by the male splashing them. The embryos have cement glands, e.g. Copeina arnoldi.

aeropsammophil = a reproductive guild (q.v.) where eggs are hidden on a beach. Spawning occurs above the high tide mark and eggs and embryos hatch at the next high tide when surf action gives the cue, e.g. Leuresthes tenuis.

aesthetic fsihing = capturing fish for display or other appreciation, not for food, sport or industrial reasons, cf. anaesthetic fishing.

aestival pond = 1) a pond containing some water throughout the year but freezing to the bottom in winter, thus supporting only a temporary fish fauna.

aestival pond = 2) a pond existing only in summer.

aestivation = dormancy during the dry season or summer, e.g. in Dipnoi. Also spelled estivation.

af = acre-foot.

aff. = abbreviation for affinis (related to but not identical with, affinity, relationship, sometimes misleadingly employed as a synonym for phenetic similarity (or akin to)).

afferent = leading towards.

afferent branchial arteries = those arteries that receive blood from the ventral aorta, extending along the gill arches and sending capillaries into the gill filaments where they join branches which become the efferent branchial arches and so are involved in gaseous exchange.

affinis = related to but not identical with, affinity, relationship, sometimes misleadingly employed as a synonym for phenetic similarity (or akin to).

affluent = a stream or river that flows into a larger one or to a standing water body; a tributary; influent, although this may be restricted to a lake having a single inflowing stream (or influent).

afin = affinis.

aflaj = plural of falaj, a term for a qanat in the Arabian Penisnula (an underground water channel constructed in alluvial fan material to tap the water table and provide a constant flow of water. Mostly found in the Middle East and a habitat there for fishes. Called karez in central Asia and Afghanistan and foggara in North Africa).

aflatoxin poisoning = a mould-based poison or mycotoxin found in some dried aquaria foods kept under warm and damp conditions. Fish exhibit poor growth and anaemia and may die. The mould species involved are Aspergillus spp.

affluvial = adfluvial.

AFO = number of vertebrae anterior to the anal fin origin, e.g. in larval fishes.

after gibb = to gibb (q.v.) herring after they have been salted in the round.

afterbay = the tail race or reservoir of a hydroelectric power plant at the turbine outlets.

agamy = the condition where no lasting bond is formed between a spawning pair, the male and female separating after spawning, e.g. in some Cichlidae.

agape = with jaws open; gaping.

agastric = lacking a stomach. Some fishes, such as herbivorous Cyprinidae, lack a true stomach.

age = the number of years of life completed. In fisheries indicated by a numeral, e.g. age 5 or age V. Since any fish is only age 5 for a moment, the numeral is often followed by a plus sign to indicate the year of life, e.g. 5+ is a fish in its sixth year of life. Freshwater and saltwater age can be indicated by a period, e.g. 2.3 represents 2 winters in fresh water (not counting the incubation period for fish eggs that overwinter) and 3 years in salt water.

age at first capture = the age at which fish are first caught commercially.

age at first maturity = mean or median age at first maturity when 50% of a cohort spawn for the first time.

age at recruitment = the age at which fish are recruited to a fishable stock.

age class = individuals of a given (same) age within a population, e.g. all four-year-olds. Usually given in years but may be shorter periods, particularly in the tropics. The age class changes every year in contrast to year class which is always the same, e.g. a fish born in 1995 will always be in the 1995 year class but in 1998 will be in age class three.

age composition = the proportion of different age groups of fish in a population or in a catch. A healthy population has a wide range of age groups.

age determination = the age of fish may be determined by counting the annual rings on a scale (by microscopic examination, projection of the scale or its celluloid imprint with a scale projector, or projecting a photographic negative of the scale), or in bony parts such as vertebrae, otoliths, opercular series of bones, pectoral spines; by the known age method (growing fish in ponds or tagging fish in the wild and recapturing them at intervals); by the length frequency method (the different age groups tend to be different lengths apparent when the sizes are grouped in a length frequency graph, from which age may be deduced). Age estimation is often a preferred term because of uncertainties in ageing methods.

age distribution = the number or percentage of individuals in each age class of a population; age structure.

age estimation = age determination.

age frequency = a breakdown of the different age groups of a kind of fish in a population or sample. Also called age structure.

age group = a group of fishes of a given age, e.g. a fish born on 1 May is in age group 0 until the same date in the subsequent year when it enters age group 1 (or I), a year later age 2 (or II), etc.

age of fishes = the period of time in the earth's history dominated by fishes - the Silurian and Devonian periods.

age of maturity = the age when 50% of the fish of a given sex are considered to be reproductively mature.

age of phase inequality = age of tide.

age of recruitment = the age when fish are considered to be recruited to the fishery, i.e. become vulnerable to the fishing gear. In stock assessments, this is usually the youngest age group considered in the analyses, typically age 0 or 1.

age of tide = the time interval between new or full Moon and the maximum effect of these phases upon range of tide or speed of the tidal current.

age specific = the dependence of a factor, such as fishing mortality, on the age of fish.

age specific fecundity = fecundity or egg potential related to age.

age specific mortality = mortality expressed as a function of age.

age specific survival rate = the average proportion of individuals in a particular age group that survive for a given period.

age structure = the number or percentage of individuals in each age class of a population.

age validation = confirming that annual growth rings on bony parts do conform to a year's growth.

age-cohort analysis = the proportion of each age-group participating in an activity currently used to predict the future sizes of each age-group.

age-group = a term denoting the age in years of a fish, or the number of calendar years in which it has existed, as O, I, II, III, etc; the cohort of fish of a given age, e.g. the five-year-old age-group. Unfortunately a standard definition has not been established.

age-length composition = age-length key.

age-length curve = a curve showing the relationship of age and length, a simplified form of an age-length key.

age-length key = a method of assigning ages to fish, given length measurements. Used to convert catch-at-size data into catch-at-age data. The keys specify the probability that fish of a given size belong to one of several age groups.

age-slicing = cohort slicing (a method used to assign ages to fish, given length measurements, e.g. used to convert catch-at-size data into catch-at-age data before the application of age-structured assessment models. Cohort slicing assumes that there is a one-to-one correspondence between length and age, i.e. the approach ignores individual variability in growth).

age-structured assessment = an assessment of the status of a fish stock, based on the relative abundances of fish of different ages in the stock.

age-structured production model = a stock assessment programme based on a deterministic form of a stock-recruitment relationship, with non-equilibrium tuning of abundance indices. Abbreviated as ASPM.

ageing = the process of determining the age of a fish or population of fishes. A fish that is less than 1 year old (counted from time of spawning by its parents) is a subyearling, or zero-age. A yearling fish is more than 1 year and less than 2 years old. Ages may be expressed as years or as year with a + sign, e.g. 3+ is a fish in its fourth year of life. Strictly, this term should be used only for the process of becoming older and the associated changes in an individual.

ageing technique = a method of determining the ages of fish, most often done by counting rings in hard parts of the fish body, such as otoliths, scales, opercula or vertebrae.

agent = the representative in a fishing settlement of a St. John's fish merchant.

agger = double tide (a high water consisting of two maxima of nearly the same height separated by a relatively small depression, or a low water consisting of two minima separated by a relatively small elevation).

aggregate = a group of species, other than a subgenus, within a genus, or a group of species within a subgenus, or a group of subspecies within a species. The aggregate can be indicated by a species-group name interpolated in parentheses.

aggregated fishery data = pooled data. Such data is compiled so that confidential or proprietary data, e.g. on detailed fishing activities of individual fishers or vessels, cannot be determined either from the present release of the data or in combination with other releases.

aggregating device = artificial or natural floating objects placed on the ocean surface, often anchored to the bottom, to attract several schooling fish species underneath, thus increasing their catchability. Used with tuna, for example. Also called fish attracting device. Abbreviated as FAD for fish aggregating device.

aggregation = 1) a group of fishes in close proximity, usually of the same species, most of which are not oriented or moving in the same direction, usually responding independently to a common stimulus, e.g. food; as opposed to a school, q.v.

aggregation = 2) a group of populations that make up a stock for management purposes.

aggression = behaviour meant to intimidate or damage another fish or other organism. Aggression is used to protect territory, young or to establish dominance. Predatory behaviour is not aggression.

aggressive mimicry = mimicry involving at least three species. A predator resembles a non-aggressive species such as a cleaner (q.v.) and thus can attack misled clients who think they are about to be cleaned.

aggressor = in aquaria, a fish which attacks others as food or in defence of territory.

aglomerular = without glomeruli (q.v.). An aglomerular kidney lacks capillaries which filter water and waste from the bloodstream. Found in some Gasterosteiformes.

agonistic behaviour = interactions between members of the same species involving threat, aggression, appeasement, avoidance and retreat; social interactions.

"Ah fishsticks!" = an expression used on the TV cartoon South Park in place of swear words by Leopold "Butters" Stotch, the most innocent and gullible character.

aiker = 1) acker.

aiker = 2) chopped shellfish and other bait thrown into the water to attract fish when fishing from a pier or rock (Scottish dialect).

aimed fishing = fishing directed at a particular, identified group of fishes, such as a school located by sonar.

Ainu dog = the Ainu of northern Japan taught their dogs to catch migrating salmon. The dogs are also called Hokkaido inu.

air bladder = gas bladder, the preferable term since the composition of gases may not be identical to that of air (a thin membranous, sometimes alveolated sac in the dorsal portion of the abdominal cavity. Composed of three layers, the tunica externa, the submucosa or middle layer and the tunica interna, all q.v. Contains a varying mixture of gases, not identical to the composition of air. May be one, two or three chambered. May be connected to the gut by a tube, the ductus pneumaticus (then called physostomous) or unconnected (then called physoclistous). May function as one or more of:- hydrostatic organ, sound producing organ, sound receptor, respiratory organ. Often lacking in bottom fishes. Sometimes called swim bladder, also a less appropriate term. An item in Chinese cuisine. Used to make isinglass, q.v.).

air blast chilling = cooling fish product with a blast of cool air to a temperature just above 0°C.

air blast freezing = freezing fish product with high velocity cold air to -35°C.

air boat = a boat with a very shallow draft, powered by an aircraft engine turning an air propeller. Used by anglers.

air breathing fishes = a general term for those fishes that can use atmospheric oxygen by means of an accessory respiratory organ, in addition to their gills. Includes fishes in the Clariidae, Channidae, Belontiidae, Osteoglossidae and the lungfishes (Dipnoi).

air bubble curtain = air curtain (1) and (2).

air curtain = 1) air bubbled through perforated pipes as a barrier to fish movement.

air curtain = 2) air bubbled through perforated pipes laid along the sea floor, forming a curtain of bubbles and a path which fish follow or are directed into a stop seine enclosure.

air embolism = gas bubble disease (supersaturated gases (>115-125%) in water entering the the body fluids of fish causing bubbles, an embolism. Often seen in gills, eyes, skin and yolk sacs where membranes are the most gas permeable. Fish often swim upside down or vertically, sometimes looking as if they are gasping for air at the surface and may have exophthalmia. Found below power plants in winter when cold water is rapidly heated by passing through condensers, in hatcheries using borehole water and in aquaria when fresh cold water is rapidly heated).

air hole = an opening in the frozen surface of a water body.

air lift = a device that inserts air into water at depth, displacing both upwards. Used in aquaculture to remove fish from cages for harvest or to lift dead fish from the bottom of cages. Also called air lift system or air water lift.

air lift system = air lift.

air ploughing = pumping air into lower, unoxygenated layers to encourage mixing and/or oxidation of bottom sediments.

air pump = a pump which supplies air for airstones, lift tubes, under-gravel filters, skimmers, bubblers, ornamental items and other devices in an aquarium. The air bubbles serve to draw water through an under-gravel filter for example. The most common type are diaphragm pumps, though cylinder pumps are available for large installations.

air sac = gas bladder, a thin membranous, sometimes alveolated sac in the dorsal portion of the abdominal cavity. Contains a varying mixture of gases, not identical to the composition of air. May be one, two or three chambered. May be connected to the gut by a tube, the ductus pneumaticus (then called physostomous) or unconnected (then called physoclistous). May function as one or more of:- hydrostatic organ, sound producing organ, sound receptor, respiratory organ. Found in Actinopterygii. Often lacking in bottom fishes. Sometimes called swim bladder or air bladder, less appropriate terms).

air vesicle = hard, hollow spheres of bone in Clupeidae.

air water lift = air lift.

airstone = a block of porous material that is attached to the air pump, q.v., to create various bubble effects in an aquarium and to oxygenate the water.

akami = lean tuna from the back of the fish as served in a sushi restaurant.

aktino- (prefix) = ray, hence Actinopterygi, the ray-finned fishes.

al. = abbreviation of alii or aliorum, meaning others, of others.

ala = alar scale.

ala laminaris = a lateral ridge on the lower part of the cleithrum, forming a site of attachment for some of the pectoral fin muscles.

alamorkret = literally eel darkness in Swedish, a season when eels are eaten smoked, fried, grilled or stuffed, in company with schnapps.

alar scale = one of the enlarged, elongate flap-like scales at the base of the caudal fin, e.g. in Alosa, Sardina, Sardinops, Harengula. Called paracaudal organ in the anchovy. Probably related to fast swimming.

alar spine = a spine on the upper surface of the pectoral fin near the tip, in some male Rajidae.

alar thorn = alar spine.

alarmist = an individual fish which reacts by movement to alarm substances, warning other school members and drawing attention of the predator upon itself, e.g. many Cypriniformes and Gonorhynchiformes.

alarm pheromone = alarm substance.

alarm substance = a substance produced in the round or oval alarm substance cells (previously called “clubcells") in the skin of Ostariophysi (Cypriniformes, Siluriformes) and Gonorhynchiformes, and which is released upon injury of the skin. On scenting the alarm substance members of the same species, and to a lesser extent related fishes, exhibit the fright reaction (q.v.). The dispersal of the alarm substance apparently normally acts to warn of the presence of a preying predator. The alarm pheromone is hypoxanthine-3N-oxide comprising a purine skeleton with N-O functional group and sensitive to relatively weak changes in pH. Also called alarm pheromone or Schreckstoff.

Alaska Scotch cure = a modified Scotch cure, q.v., used in Alaska and British Columbia for herring processing.

alate = winged, as used in anatomical descriptions.

Albany beef = cheap sturgeon flesh marketed in nineteenth century America, in particular on the Hudson River in New York State.

albino = fish lacking pigmentation, having a white to cream colour with red eye (from the blood vessels of the retina being visible). Occurring naturally if rarely in nature, they are bred artificially in aquaria. Cave dwelling species are often albinos. Albinos are less hardy than normal fish, having physiological weaknesses and being sensitive to strong light.

Albright knot = an angling knot used to join two pieces of line of unequal thickness, e.g. a heavy leader to a light main line, or vice versa, or monofilament to wire. Various websites have animated steps showing how to tie this knot.

alcian blue = a cartilage mucopolysaccharide stain used in fish osteology along with alizarin (q.v.) for calcium phosphate in bone.

alcohol = a general term for either ethanol (ethyl alcohol) or isopropanol (iso-propyl alcohol) used to preserve fishes in museums at various concentrations in water (70-80% ethanol, 45-50% isopropanol usually). Denatured alcohol is ethanol rendered unfit for human consumption by addition of methanol (methyl alcohol or wood alcohol) or other substances and is used in some fish collections.

alderling = a freshwater fish which haunts that part of the stream overhung by alder trees (English dialect).

alec = a thick sauce or pickle made from the remains of fish from which garum, q.v., has been drawn off. One kind was made from anchovies, another of small herrings. Also spelled allec, allex and hallex.

alecithal = eggs with little or no yolk.

Alee effect = the social dysfunction and failure to mate successfully when population density falls below a certain threshold.

alevin = a young fish with a yolk-sac; larva of species in which postlarval stages are not recognized; that is, in which the yolk-bearing larva transforms directly into the juvenile, e.g. in Salmonidae; the stage from hatching to end of dependence on the yolk sac as the primary source of nutrition.

alewife = Alosa pseudoharengus (Clupeidae), reputedly named after female dispensers of ale, noted for their large bellies.

alex = fish brine. Also spelled alix or ellis. See also alec.

algae = simple rootless aquatic plants growing in relative proportion to the amounts of nutrients and sunlight available. They can affect water quality adversely by lowering the dissolved oxygen and thus affecting fish populations but they are also food for fish.

algae wafer = a form of aquarium food designed to sink for bottom feeders.

algae-eating = feeding on algae, especially in reference to fish on phytoplankton.

algaecide = a chemical compound designed to kill algae or retard the growth of algae. Also spelled algicide.

algaestat = a chemical compound that inhibits algal growth and/or reproduction.

algal bloom = the rapid growth of algae on the surface of lakes, streams, or ponds; stimulated by nutrient enrichment. The water takes on a green colour. Also called water bloom.

algal crash = the sudden death of an algal bloom with build up of carbon dioxide and ammonia, and the increase of nitrogen and phosphorus from decay resulting in the removal of oxygen, all leading to fish mortality.

algal scum = a floating layer of algae, either alive or decaying.

algal toxicosis = release of toxins from such algae as Microcystis, Anabaena and Aphanizomenon causing death in fish stocks.

algavore = feeding on algae, cf. algivore.

algicide = a chemical compound designed to kill algae or retard the growth of algae. Also spelled algaecide.

algivore = feeding on algae.

alien = any species not native (indigenous) to the area under consideration, often a politically defined area (country, province, state, etc.). It includes exotic, introduced, transplanted, non-native, non-indigenous, invasive and escaped species. May be used in the sense of a species that has not become established in the wild in the new area.

aliform = wing-like, usually in reference the pectoral fin.

alii = others. Abbreviated as al.

alimentary canal = the passage through which food passes and is digested and absorbed; includes the mouth, oesophagus, stomach, intestine and anus. Also called alimentary tract, digestive tract and gut, although the latter two might be more restrictive being areas of chemical processing and absorption only and not manipulation as with mouth and oesophagus and associated structures.

alimentary tract = alimentary canal.

alisphenoid = term misapplied in older literature to the pterosphenoid (q.v.) of fishes. It is not homologous with the alisphenoid of mammals and should not be used.

alive and kicking = alert and active, an eighteenth century expression of London fishmongers then referring to fresh fish flopping around on their carts.

alix = fish brine. Also spelled alex or ellis. See also alec.

alix water = the liquid residue in a cask after rendered oil from cod livers has been drawn off in the making of rotted oil.

alizarin = a bone specific stain (actually calcium phosphate in bone and scales), alizarin red S is used to highlight the osteology of a fish specimen. The viscera are often excised and the flesh macerated or cleared (rendered transparent) by enzymes or potassium hydroxide. Preparations are made according to various recipes.

alkaline death point = the pH at which fish die from alkalinity of water, usually about pH 11.0.

alkaline cure = stock fish, q.v., soaked in a solution of lime and soda and then in water for several days.

alkaline gland = a paired organ in the genito-urinary apparatus of Raja (and probably other skates and rays) whose cavity is fluid filled. Also called Marshall's gland.

alkalinity = the acid-neutralisng capacity of carbonates, bicarbonates and hydroxides in water; the power to keep pH from changing, important for fish as protection against acid rain. Total alkalinity is the total concentration of bases in water, expressed as mg/l of CaCO₃ or as microequivalents per litre (20 ueq/l = 1 mg/l CaCO₃).

alkalophile = fish from alkaline waters, e.g. Malawian or Tanganyikan cichlids, preferring a pH over 7, preferably around 8.

all quall = talis qualis (Latin for just as they come, e.g. a whole catch of dried and salted cod sold without differentiation of quality or size (Newfoundland)).

all's fish that comes to the net = you should take advantage of anything that comes your way (proverb).

all-female species = the production and survival of a clone by gynogenesis, q.v., e.g. in Poeciliidae, Cyprinidae.

alle- (prefix) = other, different.

allec = alec.

Allee effect = the benefit individuals gain from the presence of conspecifics, e.g. at low densities the per capita birth rate declines because of the difficulty of finding a member of the opposite sex. Also known in fisheries as depensation - mortality is depensatory when its rate (i.e. the proportion of population affected) increases as the size of the population decreases. Depensation may explain why marine fish populations like the Atlantic cod are slow to recover even when fishing is halted. Per capita mortality may increase because of changes in predator-prey interactions, mate availability may be reduced, fertilisation success may be lowered, operational sex ratios may change, and there may be a reduced intensity of social interactions during spawning. Compare compensatory mortality where the mortality rate decreases as the population size decreases.

Allen paradox = the observation that the quantity of benthic invertebrates in a river is insufficient to support the observed fish population.

allergy = humans can be allergic to fish (BWC, personal experience) although not to other seafoods such as crustaceans and molluscs. Gadus morhua allergy has been studied the most and other species are believed to be similar although not all fish species may trigger a reaction. Gad c l, a parvalbumin, is the major cod allergen. Symptoms appear within minutes to a few hours of eating fish and include swelling of the lips, tongue or throat, hoarseness, cough, hives, rashes, runny nose and watering eyes, and asthma. Potentially fatal if the throat constricts. Symptoms may be limited to nausea, vomiting or cramping diarrhea.

alley = in angling, a term for patches between emergent reeds or between reeds and the shore.

allex = alec.

allo- (prefix) = other, different.

allocation = division of a fish resource among harvesters and those needed for reproduction. The harvester can be a person, a vessel, a fishing company, a country, etc. The allocation can be absolute, e.g. a number of tonnes per country based on the TAC, q.v., or relative, e.g. a percentage of the annual allowable catch. May be based on historical harvests.

allochronic species = those species that do not occur in the same geological Period.

allochthonous = food items, organic matter, nutrients etc. that enter an aquatic ecosystem from outside.

allochthonous drainage = a karst drainage derived from surface runoff coming from adjacent impermeable rocks. Also called allogenic drainage. See also autochthonous drainage.

allogenic drainage = a karst drainage derived from surface runoff coming from adjacent impermeable rocks. Also called allochthonous drainage. See also autochthonous drainage.

allolectotype = a type specimen of opposite sex to the lectotype and chosen from the type series subsequent to the original description.

allometric growth = parts of the same organism growing at different rates (allometry). See also isometric growth.

allometry = the study of proportional growth rate differences, e.g. how head length changes with respect to increasing body length.

allomone = a chemical produced and released by an individual of one species that affects the behaviour of a member of another species to the benefit of the originator, e.g. a defense mechanism.

alloparalectotype = a paralectotype, q.v., of opposite sex to the lectotype.

alloparatype = a paratype, q.v., of the same sex as the allotype.

allopatric = refers to populations or taxa whose ranges do not overlap; geographically separated.

alloplesiotype = a plesiotype, q.v., of the same sex as the allotype.

allostasis = the physiological and other mechanisms adopted by fish to cope with stress. These generally have a deleterious effect if prolonged.

allotopic = species with overlapping ranges not occurring together.

allotopotype = a type specimen from the original type locality of the same sex as the allotype, q.v.

allotrop- (prefix) =strange.

allotrophic lake = a lake receiving organic matter from the surrounding land by runoff.

allotype = a paratype of opposite sex to the holotype and originally designated by the author, a term not regulated by the International Code of Zoological Nomenclature.

allowable biological catch = a term used by a management agency which refers to the range of allowable catch for a species or species group. It is set each year by a scientific group created by the management agency and is the subjectively estimated amount of catch of a given species from a given region. The agency then takes the ABC estimate and sets the annual total allowable catch (TAC). Abbreviated as ABC.

allowable catch = the catch allowed by a management authority to be taken from a stock of a species or group of species, by a fishery during a specified time period. Often defined as the total allowable catch (TAC). Often allocated explicitly amongst those having a right of access to the stock.

allowable catch estimate = acceptable catch estimate.

allowable quota = a share in a total allowable quota (TAC) usually divided amongst those with a right to participate in the fishery. Also called quota.

allowance = an amount set aside from a total allowable catch to allow for the expected catch of harvesters who are not subject to quota management. The quota may too hard to enforce, e.g. in an inshore fishery, and these harvesters are free to catch more than their allowance, if they can.

alloy bobbin = a light-weight, hollow bobbin on the footrope of a bottom trawl with holes to allow flooding. Also called drilled bobbin.

alluvial = adjective for alluvium.

alluvial deposits = alluvium.

alluvion = fine sediment.

alluvium (adjective alluvial) = clay, silt, sand, gravel or other material deposited by running water. Often fossil-bearing over time.

Alm's Fb coefficient = the ratio of fish caught to total benthic biomass per hectare.

almas = golden caviar, i.e., either the eggs of an albino sturgeon with a light and delicate flavour or those of Huso huso or Acipenser gueldenstaedtii at least 60 years of age with a creamy and subtle flavour. Eggs are also described as pale amber or white. In 2007, a 1.8 kg tin cost £25,000. Almas is Russian for diamond.

almost atoll = an atoll whose circular rim is less than 75% complete at low tide.

alongshore = parallel to or near the shoreline. Also called longshore.

alphabet lure - alphabet plug.

alphabet plug = a plug or crankbait shaped like a letter of the alphabet (N, O, S, etc.); used primarily for bass fishing in North America.

alpine lake = a lake in a mountainous area with a cold climate, associated with snow and ice conditions.

altagongi = haltugonga (an expression meaning "stop running" used by fishermen to check the run of a halibut that has been hooked (Shetland Isles dialect)).

alternative name = two names for the same taxon, of the same rank, published simultaneously by an author.

altithermal = a warmer period than today, about 4500-7000 B.P.

altricial = young requiring care or nursing after hatching. Opposite of precocial. Also used to describe ontogeny with large numbers of ova with low energy content, poorly-developed larvae and relatively large clutches in early maturing and slow-growing fishes.

alveolar = pocketed or pitted, honeycomb-like

alveolar ridge = a bony ridge supporting teeth.

alveoli = plural of alveolus.

alveolus (plural alveoli) = a small cavity or space; socket of a tooth; air cell of the lungs.

AM, am or a.m. = abbreviation for ante meridiem or before noon; the time before 12 noon.

amarelo cure = yellow cure (Portuguese salt cod with some of the salt removed by soaking in water between stages of washing and drying, yellowish in appearance).

amateur fisher = a fisher that takes fish for fun, sport or family food and do not sell their catch. Also called recreational fisher.

ambicolouration = pigmentation of both the eyed and blind side of flatfishes (Pleuronectiformes) in which, ordinarily, only the eyed side is pigmented. Also called hypermelanosis.

ambient = surrounding on all sides, the conditions in the environment, e.g. temperature.

ambiguous name = a name consistently used by different authors for different taxa (nomen ambiguum).

ambush predator = a predator that lies in wait for its prey rather than chasing it. See also pursuing predator and tracking predator.

amelanistic = lacking melanin.

ameni = pond smelt or sand lances cooked in soya sauce with sugar and ame, a sweet millet jelly. Usually preceded by the name of the fish (Japan).

amensalism = negatively affecting one or several species; a form of symbiosis where one of the embers suffers as a result of the relationship while the other is unaffected by it.

American caviar = 1) caviar from American species of sturgeons.

American caviar = 2) caviar from non-sturgeon species in North America such as paddlefish (Polyodontidae).

American cut = fish portions or fillets with tapering or beveled edges, rather than square-cut sides. Also called Dover cut.

American hardness = a measure of hardness used in the USA. One degree is equal to 1 mg/l.

American shore = a length of Newfoundland coast where American vessels were allowed to take bait.

ami = abbreviation for air miles, the straight line distance between two points used when describing a specimen collection locality.

amictic = lakes with a permanent ice cover and so with no circulation.

ammel = dan leno stick (a ballasted wood pole with short rigging ropes attached, functioning like the dan leno bobbin, q.v.) (northeast Scotland).

ammocoete = the larval stage of lampreys (Petromyzontiformes) which is characterized by the presence of an oral hood and the lack of a sucking disk, teeth and developed eyes. The term is derived from the genus Ammocoetes in which the larvae were placed before it was realized that they were larval lampreys.

ammonia poisoning = ammonia may build up in aquaria from fish wastes, decaying food and plant material and poison fish. Symptoms are gasping, excess mucus production, reddening skin from capillary haemorrhages, erratic behaviour. An efficient biological filtration system prevents this condition but if it does arise fish need to be moved to a mature aquarium where the nitrogen cycle, q.v., is in full operation.

ammonia tower = a type of biological filtration in aquaria which has media exposed to the air to aid in nitrification through bacterial growth. Common forms are trickle filters and rotating paddle wheel filters. The air/water mix promotes bacterial growth and the bacteria remove ammonia and nitrites. Also called a wet/dry filter.

ammonotelic = excreting nitrogenous wastes mostly as "nitrogen" (NH₃, or the ammonium ion NH₄^-). Typical of most fishes.

amnesia = a high breaking strain monofilament line used in still fishing rigs.

amnion = a fluid-filled sac in which the embryo develops in reptiles, birds and mammals. Fish are anamniotes, as are amphibians.

amniote = a classification of vertebrates to include those with an amnion.

amoc = the traditional Cambodian fish dish comprising baked fish wrapped in a banana leaf and served with coconut, chili and lemon grass.

amphi- (prefix) = both, on both sides of, e.g. amphi-Atlantic on both sides of the Atlantic, amphi-American on both sides of America, amphi-Pacific on both sides of the Pacific (these terms may include discontinuous and continuous distributions).

amphiarthrosis = an articulation that allows limited movement, as between vertebrae; cf. diarthrosis and synarthrosis.

amphibi- (prefix) = living a double life.

amphibiont = a species requiring both surface and ground waters in its life cycle. Also called amphibite.

amphibiotic = living in water during an early stage of development and on land during the adult stage.

amphibious = able to live or operate on land and in the water, e.g. mudskippers approach this condition.

amphibite = amphibiont.

amphiboreal = pertaining to an interrupted northern circumpolar distribution.

amphicelous = amphicoelous.

amphicoelous = biconcave vertebrae, having both ends hollowed out, the condition in Elasmobranchii, Amia and most Teleostomi except Lepisosteus (also spelled amphicelous).

amphidromic point = a point of zero amplitude of the observed or a constituent tide.

amphidromic region = an area surrounding an amphidromic point from which the radiating cotidal lines progress through all hours of the tidal cycle.

amphidromous = fishes which regularly migrate between the sea and fresh water (or vice versa) at some definite stage in their life cycle but not for the purpose of reproduction, e.g. Sicydium, perhaps Megalops and Chanos, some Galaxias (Myers, 1949).

amphihaline = showing a broad salinity tolerance and capable of living in fresh or salt waters.

amphimixis = sexual reproduction involving the fusion of male and female gametes and the formation of a zygote.

amphipedal progression = locomotion using the pectoral fins in a manner similar to that used by humans on crutches, e.g. in mudskippers and frogfishes. Also called crutching.

amphistylic = attachment of the upper jaw to the skull by means of a process on the palatoquadrate and the hyomandibular bone and by a direct connection between the jaw and braincase, e.g. some Elasmobranchii; basal gnathostomes, other than placoderms).

amphitropical = pertaining to a distribution of temperate species interrupted by the tropics.

amplitude = half of the peak-to-trough range (or height) of a wave.

ampulla = a swelling of the end of the semicircular canals.

ampullae of Lorenzini = Lorenzini's ampullae (the mucus filled canal system opening on the snout of Elasmobranchii, Polyodon spathula and Plotosus anguillaris. May be electric, pressure or temperature receptors).

ampullary organ = an electroreceptor consisting of receptor cells sunk into the epidermis or located in an epidermal cavity opening to the surface through a duct and pore. The duct may be filled with jelly, e.g. in certain Gymnotidae, Mormyridae and Siluroidei.

ana- (prefix) = over, back, again, backward, upward.

anaba- (prefix) = to go up, hence Anabantidae.

anabiosis = inhabiting temporary water bodies and surviving drought by suspended animation, e.g. Dipnoi.

anabranch = a diverging branch of a river which re-enters the main stream.

anacanthous = lacking dorsal fin spines. Opposite of phalacanthous.

anacat = fish that live partly in fresh water and partly in the sea and vice versa (from anadromous and catadromous).

anadrom- (prefix) = running up, to go up.

anadromous = running up; said of those fishes which spend most of their life in the sea and which migrate to freshwater to reproduce, e.g. Oncorhynchus, Stenodus, Petromyzon, Roccus, Stokellia anisodon (Retropinnidae) (Myers, 1949). The opposite is catadromous.

anaemia = deficiency of red blood corpuscles or haemoglobin; in fish a dietary disease due to a vitamin deficiency.

anaemic fish = the ice fishes of Antarctica, e.g. Chaenichthyide, which lack red blood corpuscles.

anaerobic = without oxygen, either as a presence or needed as part of a process.

anaesthetic = a chemical used to reduce a fish's movements or metabolic rate prior to some procedure such as tagging or transport. Chemicals include MS-222 and clove oil and, for fry, novocaine and sodium barbitol.

anaesthetic fishing = angling while numbed under the influence of drugs or alcohol, leads to poor catches and even drowning, cf. aesthetic fishing.

anagenesis = evolutionary change along an unbranching lineage (no new species arise) or when one species transforms into another across time.

anagram = a taxonomic name formed by the rearrangement of the letters of a word or phrase.

anal = pertaining to the anus.

anal fin = the median ventral fin or fins behind the anus. Abbreviated as A, or A1 and A2 if there are two. Also called proctopterygium or proctal fin, it functions to maintain equilibrium against rolling.

anal fin base length = the distance between the origin and the insertion of the anal fin, i.e. the length of that portion of the anal fin in contact with the body.

anal fin depressed length = the depressed length of the anal fin is the distance from the origin to the farthest posterior tip when the fin is flattened down.

anal fin height = the distance from the origin to the tip of the longest ray. Sometimes taken as the greatest vertical height from the base.

anal fin ray count = enumeration of the soft anal fin rays. In fishes where the smaller rays in front gradually grade into larger rays, these smaller anterior rays are included in the count, e.g. Ictaluridae, Esocidae, Gadidae. Where the first small rays abruptly change to larger ones, or where the first small rays are very variable or difficult to count, these are not included; the first unbranched ray reaching nearly to the tip of the fin and the remainder of the rays are then counted - this is called the principal ray count. Where the last two rays are closely approximated at the base, some authors consider them as a branched ray counting them as one (although they are not really a single branched ray). In fishes where the last two rays are not closely placed at the base, the rays are usually both counted. However some authors again count the last two rays as one. In some studies, only the branched rays of the anal fin are counted. It may readily be seen that if published counts are to be of use to others the method of counting should be stated.

anal gland = rectal gland (an evagination of the terminal portion of the intestine of Elasmobranchii. Function formerly thought to be related to digestion or excretion, but now considered to secrete high concentrations of excess sodium chloride. Found also in the coelacanth Latimeria chalumnae).

anal lappet = a small skin flap supported by an internal scale or scales over the anal fin base in Cetomimidae.

anal papilla = a fleshy protuberance through which the end of the digestive tract passes.

anal photophores = two rows of light organs, one above the base of the anal fin and the other along the ventrolateral surface of the caudal peduncle. Abbreviated as AO in Myctophidae.

anal ring = one of the dermal plates in members of the Syngnathidae forming a series of rings enclosing the body; the body ring immediately in front of the anus.

anal spine = a spine at the origin of the anal fin before the soft rays. In flatfishes this is not a true spine but the free end of the first distal anal pterygiophore under the skin which may protrude through the skin.

analog products = simulated crab, lobster and other shellfish and fish products made from processed fish flesh.

analogous = similar in structure or function but independently evolved, e.g. the hard ray in the dorsal fin of the carp and the spines in the first dorsal fin of the perch are analogous structures.

analytical operation = research study on a fish stock gathering data that cannot be obtained from commercial operations.

anamestic bone = one of a series of bones in the cheek region that fill in spaces left by the sensory pit-bearing bones; may be used for any bone lacking sensory canals. Often small, of irregular shape and variable between individuals.

anamniota = a classification of vertebrates without an amnion.

anamniote = fishes, including Agnatha, have an embryonic stage without an amnion, as do amphibians.

anastomosing = joining in a network, forming a network, e.g. river channels, blood vessels.

anatomy = the structure of organisms, often revealed by dissection.

anaulacorhizid = vascularisation of a tooth root through scattered foramina of equal size on both outer and inner faces, e.g. in Hexanchidae. A secondarily anaulacorhizid condition occurs where the median groove of a holaulacorhizid type of root is totally overgrown to form a closed tube internally connected or merged with the pulp cavity (Herman et al., 1994).

anazygalia = zygalia (four small cranial bones in Osteolepiformes, perhaps formed from elements of the second to the fourth vertebra, a segment of the primordial cranium. The anazygalia are located dorsal to the chorda dorsalis, the catazygalia ventral to the chorda dorsalis).

ancestor = any organism, population, or species from which some other organism, population, or species is descended by reproduction.

anchialine = anchihaline.

anchihaline = referring to an aquatic habitat with restricted open air exposure, one or more connections to the sea (but not a surface connection), and influenced by marine and terrestrial ecosystems. Found in volcanic and limestone areas, e.g. the bythitid genus Lucifuga of Cuba and the Bahamas. Also spelled anchialine.

anchor = a metal device lowered on a line or chain and used to secure a vessel to the sea bed. Also used to secure nets. Anchors have flukes (points that dig into the bottom or grab rocks; the flattened part is called a palm) connecting by arms to a crown, a shank (a vertical bar) rising from the crown, many also have a stock (a horizontal bar that prevents rolling over) which passes through an eye, and a ring (where the rope or chain is attached). There are many different type and sizes of anchors, e.g. see killick, Admiralty pattern anchor, ice anchor and trawl anchor.

anchor (verb) = to affix an object, such as a net, to the sea floor, using an anchor or similar device. An anchor is set, by which it is pulled to engage the flukes in the sea bed or against rocks. However its weight alone may prevent movement of a boat or net.

anchor buoy = a large, spherical buoy supporting and marking the various ropes connected to the main anchor used in Danish seining.

anchor ice = frazil ice that collects on the stream or lake bed, or extends down to the water bottom.

anchor net = set gillnet (a gill net fixed to the bottom or a distance above it by anchors or ballast. Also called straight net, sunk gillnet, sunken gill net, sunk net).

anchor rope = 1) a rope connected to an anchor or anchor chain.

anchor rope = 2) a cable-laid rope acting as a spring between the anchor wire and anchor buoy in a Danish seine. Also called anchor trot.

anchor seine = Danish seine (a seine or cone-shaped otter trawl which is hauled over an area of about 2 square kilometres to a stationary vessel from an anchor buoy, the very long towing ropes disturbing clouds of mud which help herd the fish into the net. Also called Danish seine trawl or Danish trawl).

anchor surface net = a set gill net fixed to fish near the surface. Also called surface gill net.

anchor tag = an alphanumeric or colour-coded tag attached through the flesh near the dorsal fin of a fish. A special injection device allows numerous fish to be tagged rapidly.

anchor trot = anchor rope (2).

anchor worm = a copepod crustacean parasite of the genus Lernaea found on fish gills. No intermediate host. Worm-like in shape and often quite large and obvious, forming ulcers at the attachment point, and inducing scratching and flashing through irritation. Heavy infestations, especially of small or larval fish, may lead to hypoxia through increased respiration. Found in freshwater fishes, particularly cyprinids in culture and as bait minnows.

anchored fish aggregating device = a fish aggregating device (q.v.) that is anchored close to the coast and used in artisanal fisheries.

anchored gillnet = bottom-set gillnet (a net anchored on or close to the bottom by anchors and ballast).

anchored line = a fishing line fixed to the sea bed at one end or at several points along its length.

anchored trap = a pound net (q.v.) or fyke net (q.v.) set in deep water and maintained in place by lines and anchors. Usually set horizontally but may be set vertically under ice, e.g. for turbot in the Baltic Sea.

anchovy = common name for various fish species in the fishes in the family Engraulidae, best known in North America for their salty and decried topping on pizzas but an important and tasty element in European cuisine. Part of caesar salad, Worcestershire sauce and often the basis for garum (q.v.). The various species occur in vast numbers as a schooling fish in waters worldwide.

anchovy butter = anchovy paste mixed with butter.

anchovy cream = anchovy paste mixed with vegetable oil.

anchovy essence = a compound of pounded anchovies and various herbs. May be canned.

anchovy paste = ground anchovies covered with salt, saltpetre, bay salt, sal prunella and cochineal. Sold in jars or cans.

anchylose = ankylose.

ancillary collection = material retained in addition to the main specimen in a collection, e.g. frozen tissue, thin sections, body parts, DNA, etc.

ancillary product = additional use, other than the primary one, of a fish, e.g. in a fish used for flesh, use of internal organs, of heads, and as fishmeal, etc.

andro- (prefix) = male human.

androdioecious = adjective for androdioecy.

androdioecy = possessing a single gonad that produces both eggs and sperm. Eggs are fertilised internally and most offspring are clones. Found only in the mangrove killifish (Kryptolebias marmoratus) in vertebrates. Some males exist, the numbers varying between populations, allowing greater genetic diversity, while androdioecy allows the fish to colonise new habitats.

androgamone = sperm secretions which depress the activity of sperm in the male genital duct and dissolve the egg membranes.

andropodium = a modified anal fin of Hemiramphidae used to transfer sperm to females. Also cited as being the modified anal fin in Goodeidae.

anerytheristic = lacking red pigmentation.

anesthetic = anaesthetic.

anfish = a legendary hairy fish of the lower Tigris-Euphrates basin in Iraq; possibly a marine mammal entering from the sea or the otter.

angel fillet = block fillet (a fillet comprising muscle mass from the side of the fish, usually joined at the back or belly. Also called cutlet, double fillet or when smoked golden cutlet).

angio- (prefix) = vessel.

angiogenesis = development of new blood vessels, as in embryos and tumour formation. See also shark cartilage.

angishore = 1) a man too lazy to fish (Newfoundland).

angishore = 2) a migratory fisherman from Newfoundland who conducted a summer fishery from a fixed station on the coast of Labrador.

angle = 1) the bony protuberance posterior to the jaw gape where the angular, articular and quadrate bones join. Ventrally directed and especially prominent in some larval fishes.

angle = 2) old word for a hook. Hence to angle, angler.

angle = 3) to fish with a hook, rod and bait.

angle = 4) to scheme, or to try and get something by devious or illegal means.

angle = 5) a sharp bend in a river.

angle = 6) a curved inlet of a lake or pond.

Angle = 7) a member of a Germanic people that migrated to England from a fish hook-shaped area of southern Jutland in the 5th century A.D., hence England.

angle-bow = a running noose or slip-knot, especially on the end of a stick, used to catch fish (English dialect).

angle-bowing = poaching fish by means of an angle-bow.

angle-dog = an earthworm used for freshwater fishing (Newfoundland).

angle-rod = a fishing rod.

angle iron chain = chain bracket (a chain used on an otter board in pace of a bracket. Also called back board chain, board chain, chain triangle, towing chain).

angle with a silver hook = a failed fisherman who buys his fish to take home, using silver coins in the past.

angler = 1) a person using an angle to catch fishes, and usually a rod and line too; a recreational fisher. The fish may be released or kept as food but they are not sold. Angler encompasses both sexes in contrast to fisherman.

angler = 2) a pilferer having a stick with a hook at the end to steal goods from shop windows (archaic).

angler day = one person angling for any part of one day.

angler survey = a survey of anglers and their catches either off-site by mail, email, telephone, door-to-door, etc. or on-site by access, roving, aerial, etc.

anglerfish = a member of the Order Lophiiformes, comprising over 313 species in 18 families. They have a fishing apparatus developed from the first ray of the spiny dorsal fin comprising the illicium (q.v.) or fishing rod tipped by the esca (q.v.) or bait. The apparatus is used to attract other fishes close enough to be gulped down.

anglers association = a group of individuals paying an annual fee to fish in waters owned or leased by the association. Membership may be in the many thousands and the association can set rules for fishing gear and times, angling contests, stock waters with fish, and influence national policies on fish management. Also called fishing club or fish club.

angleworm = a small earthworm used as bait in angling, usually for small stream trout and panfish, cf. night crawler.

angling = fishing with a rod and reel or a rod and line, usually for sport but also an effective way to catch some species for research purposes (or so ichthyologists maintain) and similar methods are used for some commercial fishing. Strictly uses an angle or hook but generally synonymous with sport fishing, q.v. See also recreational fishery.

angling association = anglers association.

angling cove = a receiver of stolen goods.

angling device = the modified dorsal fin on anglerfishes (Lophiiformes) used to attract prey.

angling for farthings = begging out of a prison window with a cap or box let down on the end of string (archaic). Farthings were a coin worth a quarter of a penny.

angling machine = an automated rod and line system on the side of a vessel. The machine can jig to catch the fish, rotate to bring the fish on deck, and jerk to release the fish from the hook.

anguilliform = 1) eel-like in shape.

anguilliform = 2) sinuous type of swimming as in an eel. See also carangiform, labriform, ostraciform, thunniform.

angular = the triangular, paired dermal bone on the posterior ventral corner of the lower jaw. Also applied to the dermal bone of the lower jaw which articulates posteriorly with the quadrate, in which case the preceding bone is known as the retroarticular. In mammals this bone becomes the malleus of the inner ear.

angulas = deep-fried elvers (young Anguilla anguilla), a Basque delicacy.

angulate = having definite angles or corners.

angulo-retroarticular = retroarticular (the triangular, endochondral, dermal or mixed origin bone on the back, hind corner of the lower jaw. Often called the angular, Bridge's ossicle a, or lower articular).

anguloarticular = articular (the deep, endochondral bone of primitive acanthopterygians in the middle of the lower jaw between the dentary and the angular (or retroarticular) which articulates with the quadrate. It is later invaded by the angular. Divided into the distal part (wanting in Teleostomi) and the proximal part. Occupies the position of Bridge's ossicles b and c in Amia. Found as a distinct structure in Amia, Lepisosteus, Polyodon and Acipenseridae).

angulosplenial = articular (the deep, endochondral bone of primitive acanthopterygians in the middle of the lower jaw between the dentary and the angular (or retroarticular) which articulates with the quadrate. It is later invaded by the angular. Divided into the distal part (wanting in Teleostomi) and the proximal part. Occupies the position of Bridge's ossicles b and c in Amia. Found as a distinct structure in Amia, Lepisosteus, Polyodon and Acipenseridae).

animal pole = the location on the fish egg where polar bodies emerge. It corresponds to the point of fertilisation just below where the sperm penetrates the chorion through the micropyle.

animal-vegetal axis = a line passing through the animal and vegetal poles of the embryo before epiboly.

anisakiasis = a disease caused by a nematode parasite. Anisakis can infect humans causing gastric problems if raw or lightly processed fish, e.g. cold smoked, is consumed. Freezing below -18°C followed by frozen storage for 24 hours kills this parasite. The parasite is found in the viscera and muscles of such fish as herring. Marine mammals are the definitive host. Also called anisakinosis.

anisakinosis = anisakiasis.

aniso- (prefix) = unequal, uneven.

anisogamy = reproductive products of unequal size (eggs and sperm).

anker = a barrel containing, and a measure, of salmon (Orkney and Shetland dialect).

ankimo = monkfish liver as served in a sushi restaurant.

ankled = said of fishing nets twisted together. See also hankle.

ankylose = to fuse together, e.g. fusion of two bones or teeth to bone to form one part. Sometimes spelled anchylose.

anlage (plural anlagen, German) = the initial clump of cells from which develops an organ or structure; primordium.

anlagen = plural of anlage.

annatto = a vegetable dye used for colouring smoked fish.

anno = to row against the wind to keep a boat from drifting, while rod or handline fishing is going on (Caithness dialect).

annosman = the man who annos the boat.

annual canvas = a compilation of available fishery records made annually.

annual fish = a fish which normally completes its life cycle in a year and dies, only the eggs surviving, e.g. certain South American and African cyprinodonts dwelling in ponds which disappear in the dry season, Austrofundulus, Rachovia, Aphia pellucida, Cynolebius.

annual flood = the highest annual peak discharge of a river.

annual growth rate = the increase in weight of a fish over one year (final weight divided by initial weight). Abbreviated as h or h (Ricker, 1975).

annual migrant = a fish that makes regular yearly migrations for spawning and/or feeding.

annual mortality = the percentage of fish dying in one year due to natural causes. May also include those taken through fishing.

annual mortality rate = the ratio between the number of fish which die during a year from causes other than fishing and the number alive at the beginning of that year. Also called annual natural mortality rate, conditional natural mortality rate, seasonal natural mortality rate. Abbreviated as m or n.

annual natural mortality rate = annual mortality rate (the ratio between the number of fish which die during a year from causes other than fishing and the number alive at the beginning of that year. Also called conditional natural mortality rate and seasonal natural mortality rate).

annual production = 1) tonnes of market-sized fish produced by an aquaculture facility in one year.

annual production = 2) the amount of fish produced by a defined area of river or lake.

annual ring = a growth ring formed over the course of one year.

annual species = one in which free-swimming individuals live for less than one year, their fertile eggs hibernating in soil during the dry season, e.g. some rivulin Cyprinodontidae.

annual surplus production = the assumption in fisheries that there is a biomass removable without changing population size.

annual total mortality rate = the number of fish which die during a year divided by the initial number. Also called actual mortality rate, coefficient of mortality. Abbreviated as A.

annual turnover = 1) the total biomass produced in one year.

annual turnover = 2) the spring and fall mixing of water in a lake caused by wind, annual air temperature cycle and heating from the sun.

annualism = the state of being an annual species.

annular = ring-shaped.

annular drainage system = a drainage system arranged in a circular fashion around a central basin. See also dendritic, deranged, parallel and rectangular drainage systems.

annular sclerite = annulus.

annuli = plural of annulus.

annulled name = an originally available name that has been suppressed by the International Commission on Zoological Nomenclature and consequently becomes unavailable for purposes of priority.

annulled work = a publication that the International Commission on Zoological Nomenclature has ruled must not be used for purpose of nomenclature.

annulment = the suppression by the International Commission on Zoological Nomenclature of an available name as unavailable for the purposes of priority and homonymy, and the ruling of a work as unavailable.

annulus (plural annuli) = a ring or rings on a fish scale or in a bony or cartilaginous structure corresponding to a year of growth. In a scale usually consists of closely arranged ridges (circuli). An accessory annulus is a ring caused by retarded or temporarily terminated growth that does not represent an annual cycle. In the tropics annuli may indicate spawning rather than growth.

anomaly = departure from normal.

anoman = any animal species other than Homo sapiens; from "animal other than man".

anomen = plural of anoman.

anonymous = of a name, nomenclatural act or work whose authorship is not stated. Also where the identity of an author cannot be determined from the work itself.

anoxia = the lack of oxygen in an environment.

answer = a bite in fishing.

Ant = a photophore at the anterodorsal margin of the orbit.

ante- (prefix) = before, in front of.

antecedent stream = a stream already in place before the rise of a mountain range, subsequently cutting through the rock at the same rate as the mountains rise and so maintaining its position. This has consequences for fish distribution, dispersal and migration.

antecedent year = the year when fish were spawned.

antennulae microvillares = mucopolysaccharide threads or tufts, the mucus filaments on the outermost layer of skin.

antepenultimate = the third from the end; one preceding the penultimate.

anteriad = in front of; towards the front end.

anterial = towards the anterior end.

anterials = teeth on the anterior field of the oral disc of lampreys (Petromyzontidae).

anterior = in front; front (also used for towards the front end, strictly anteriad). Opposite of posterior.

anterior anal photophores = the row of light organs just above the base of the anal fin in Myctophidae (abbreviated AOa).

anterior cardinal vein = paired veins draining blood from the head into the common cardinal veins.

anterior cerebral vein = a vein draining blood from the rostrum and eye into the lateral head vein, q.v.

anterior circumorals = the first row of anterials.

anterior field = a wedge-shaped section of a scale encompassed by lines from the focus to the antero-lateral corners of the scale. This field is usually embedded in the skin and not exposed.

anterior intestinal artery = a branch of the coeliac artery that serves the enlarged proximal loop of the intestine and the intestinal diverticula.

anterior-posterior axis = the principal axis of the embryo. Also called rostrocaudal axis and embryonic axis.

anterohyal = ceratohyal (the bone articulating dorsally with the interhyal, anteriorly supporting some branchiostegal rays and ventrally joining one or two hypohyals).

anterolateral photophores = an old name for VLO photophores (q.v.).

anterorostrum = antirostrum.

anthelminthic = a medication used against helminth or worm infestations of fishes.

anthropogenic = involving the impact (usually negative) of mankind on nature.

anti- (prefix) = opposite, against.

anti-fouling agent = a paint used to protect ships or aquaculture cages from attaching organisms. Now regulated in aquaculture because of their build-up in fish tissues and replaced by biodegradable and less toxic products.

anti-freeze = natural proteins in the blood of polar and cool-temperate fishes that prevent formation of ice crystals down to an exterior temperature of -6°C.

anti-helminthic = anthelminthic.

anti-kink = any device used to prevent twisting of fishing line; in angling often achieved by having swivels, q.v.

anti-nutrient = a component of plants that can be toxic to fish in high concentrations or decreases the ability to absorb minerals from food. Presents problems in using plants as food in aquaculture.

anti-reverse = a system, such as a switch, preventing fishing reels from spinning in reverse.

anti-tangle lead = a lead weight used to sink the bait in angling having a long length of silicone tubing on either side to protect the line from abrasion.

anti-tangle rig = a ledgering rig used by anglers mostly for carp. Comprises booms, swivels and tubing to help prevent tangles during casting.

antibiotic ice = ice containing a small amount of an antibiotic such as tetracycline used to extend the shelf life of fish. Illegal in many countries because it promotes antibiotic resistance.

antibody = a protein (an immunoglobulin or Ig) produced by the B-lymphocytes in the blood in response to the introduction of a foreign substance, an antigen.

antiboreal = of the south temperate region.

antigen = a substance which induces the formation of antibodies; used to compare relationships among species based on those sharing the same or more antibodies (serum proteins).

antimere = the corresponding element on the opposite side of a bilaterally symmetrical organism, as fishes are.

antimycin A = a chemical produced by streptomyces bacteria and used in a commercial preparation as a piscicide, e.g. in the catfish industry. It inhibits adenosine triphosphate (ATP) formation, the nucleotide necessary for transport of chemical energy within cells.

antioxidant = a food additive that reduces oxidation of lipids and thus rancid flavours in fish, fish oils and fish meals, e.g. vitamins C and E.

antipodean = referring to opposite sides of the world.

antirostrum = the anterior and dorsal projection of the sagittal otolith, dorsal to the sulcus.

antiserum = a blood serum with specific antibodies.

antitropical = the distribution pattern where a group is found north and south of, but not in, the tropics. Includes bipolar, bitemperate distributions, e.g. Sardinops, Engraulis, Squalus, Zeus.

antitype = paratype (every specimen, other than the holotype, in the type-series; all the specimens on which the author bases the series, except any that (s)he refers to as variants, or doubtfully associates with the nominal species, or expressly excludes from it). Paratype is preferred.

antivenene = antivenin.

antivenin = a serum used against venoms such as that of stonefish (Synanceia).

antorbital = a small, paired dermal bone lying lateral to the nasal bone in front of the eye. Sometimes included in the suborbital or infraorbital series because the infraorbital canal crosses it, e.g. in Amiidae, Lepisosteidae, Elops, Osmeridae, some Siluridae.

antorbital organ = a photophore on the front and lower edge of the orbit which may manifest itself as the photophore Vn or Dn or as the suborbital light organ.

antron = a synthetic yarn having long and sparkly fibres used in artificial fly tying.

antrorse = angled forward or pointing anteriorly; opposite of retrorse.

ants' eggs = a commercial food for aquarium fish, no longer sold, comprising dried ant pupal cases of no nutritional value.

anus = the posterior opening of the digestive tract by which it communicates with the exterior and through which faeces are voided. Also called vent, although the vent is the opening for reproductive and kidney products too.

AO = a row of photophores along the base of the anal fin and lower side of the caudal peduncle (not including the Prc's at the base of the caudal fin) in Myctophidae. Usually divisible into AOa mostly above the anal fin base and AOp mostly on the caudal peduncle. In some older works AO refers to the antorbital photophores.

AOa = a row of photophores mostly above the anal fin base in Myctophidae.

AOp = a row of photophores mostly on the caudal peduncle in Myctophidae.

aorta = the main blood vessel supplying blood to the body from the heart.

aortic arches = the pairs of arteries running through the branchial arches, connecting the ventral aorta with the dorsal aorta (or for the first two arches to the internal carotid artery). The last four carry the blood supply to and from the gills.

aortic radices = the paired roots of the dorsal aorta, joining posterior to the entrance of the last efferent artery to form the dorsal aorta.

ap. = abbreviation for apud, meaning in the work of; used in citing the work of an author contained in another work.

aparietal = a form of skull where the parietals are absent, e.g. in Syngnathiformes, Siluridae.

apatite II = a proprietary preparation of fish bones used in removing heavy metals from soil and water. The metals are chemically bound into new minerals that do not dissolve or leach over extremely long time periods.

apex (plural apices, adjective apical) = the free tip of a fin, e.g. in sharks.

apex predator = a fish at the top of the food chain, relying on smaller fishes for food.

aphagous = adjective for aphagy.

aphagy = lacking the ability to feed.

aphakic space = the space in the pupil which is not occupied by the lens. The space may be circumlenticular, around the lens as in Stomias, ventral as in Omosudidae, some Myctophidae and Paralepidae, or rostral as in Scopelosauridae. A rostral aphakic space may enhance the forward binocular field of vision.

aphetohyoidean = the primitive condition of jaw suspension for gnathostomes (jawed fishes and relatives) where there is a non-suspensory hyoid arch behind a full post-mandibular gill slit.

aphotic = areas never reached by natural light in the deep ocean (deeper than about 800 metres). No photosynthesis occurs.

aphrophil = a reproductive guild (q.v.) of a froth nester, where eggs are laid in mucous bubbles made by the fish. Embryos have cement glands and well-developed respiratory structures, e.g. in Anabantidae and some characins.

aphytal = the plantless zone of a lake bottom.

apical = at the apex, tip or end. The apical field of a scale is the posterior end normally exposed when in its natural position. The side exposed to water in gills.

apical margin = the rear edge of a scale. Also called posterior margin.

apices = plural of apex.

apkallu fish = one of seven Babylonian wise men, dressed in the skin of a fish. These wise men lived before the Flood, and were sent by the fish god Ea to teach wisdom to humans and to protect and purify them.

aplacental = viviparous reproduction in which embryos are not connected to their mother's blood supply by a placenta, as is the case in some sharks.

aplacental viviparity = also called ovoviviparity (production of eggs that are fertilised and hatch inside the mother but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother. The young are born as miniature adults, free-swimming and feeding).

aplesodic = said of a cartilaginous pectoral fin where basals and radials do not reach the border and so do not offer the support seen in the plesodic fin, q.v. More highly derived fish may have other support for the distal fin region such as ceratotrichia, q.v.

apparent digestibility coefficient = nutrient ingested-nutrient egested/nutrient ingested. Not all food eaten or ingested is absorbed, the rest is egested as faeces . The absorbed portion is expressed as a percentage according to the above formula.

apo- (prefix) = away from.

apod- (prefix) = without feet.

apode fishes = fishes without pelvic fins, e.g. Anguilla.

apogean tidal current = a tidal current of decreased speed occurring monthly as the result of the Moon being in apogee (the point in the orbit of the Moon farthest from the Earth).

apogean tide = a tide of decreased range occurring monthly as the result of the Moon being in apogee (the point in the orbit of the Moon farthest from the Earth).

apogenotype = a type specimen fixed through substitution, e.g. when a genus is renamed through homonymy, the type species automatically becomes the type of the new genus.

apomorph = a derived character differing from the ancestral condition.

apophyses = plural of apophysis.

apophysis (plural apophyses) = a narrow expansion protruding from the body of a bone.

apopyle = the anterior opening of the tube formed by the claspers.

apomorphy = a state derived by evolution from a primitive state (plesiomorphy); applied to a character, not a taxon. It relates to the compared character state and the hierarchical level considered, i.e. the character is apomorphic in relation to one state but plesiomorphic to another.

aponeurosis = flattened tendon.

aposematic = referring to a colour or structure that warns of a special means of defense against a predator.

apotype = a specimen used to supplement the description of a type.

apotypic = a term coined to replace apomorphy as the latter strictly applies only to morphological characters.

apparatus Weberei = Weberian apparatus (four bones and associated tissues connecting the gas bladder to the inner ear and conveying pressure changes and sound. Usually the definition includes the first four vertebrae (two and three may be fused), a supporting unit or pars sustentaculum comprising two transverse plates projecting downwards from the fourth vertebra enclosing a circular space for the aorta and the neural complex comprising modified neural arches and spines. Found in the Cypriniformes and Siluriformes).

apparent digestibility coefficient = the value for the food absorbed from diet and not excreted in faeces; nutrient ingested - nutrient egested/nutrient ingested. Abbreviated as ADC.

apparent prevalence = the proportion of test-positive fish in a target population.

appearance = a visual assessment of a fish product based on shape, colour, gloss/dullness, translucency/opacity and surface texture.

appendage = any substantial projection form the body. The pectoral and pelvic fins are paired appendages.

appetency = an instinctive inclination or propensity in animals to perform certain actions, e.g. a male Betta splendens will display when sighting itself in a mirror.

appertisation = canned fish; a term used to avoid confusion with semi-preserves, q.v.

appetite mood = in angling, used to describe a fish's attitude to feeding. In a positive mood the fish is actively feeding, in a neutral mood a lure or bait will be taken if presented properly, and in a negative mood will not take food, a bait or a lure unless it is by an involuntary reflex action such as a strike at a moving object.

appetitive behavior = 1) purposeful feeding behaviours resulting in the identification and location of specific food items.

appetitive behavior = 2) searching for the stimulus that can release the activity, e.g. a stickleback that has left its nest shows this behaviour when returning to resume fanning of the nest.

application= the use of a name to denote a taxon.

application to the Commission = any zoologist may submit nomenclatural problems to the Commission. These are published in the Bulletin of Zoological Nomenclature.

appressed = held flat against the body, e.g. appressed pectoral fin. See also adpressed.

approach velocities = water velocities at or near the face of a fish screen, q.v.

approved = given approval and promulgated by the International Commission on Zoological Nomenclature.

approved name = one given approval by the International Commission on Zoological Nomenclature for use in nomenclature.

April fish = usually appearing as poisson d'Avril, French for April fool, based on a newly spawned, naive and easily-caught fish. A paper fish is attached to a victim's back without him noticing. Occasionally appearing in its English translation.

aproctal bone = the ventral element in the priapium of the Phallostethidae on which articulate the ctenactinia (q.v.). Also called axial or pelvic bone.

apron = 1) the false belly of the cod end of a trawl used as a chafing gear.

apron = 2) the netting floor of a bag or stake net.

apron gill net = an L-shaped net comprising a vertical back wall and a horizontally floating apron.

apron reef = the initial stage of a fringing reef, being discontinuous and covering a small area.

apud = meaning in the work of; used in citing the work of an author contained in another work. Abbreviated as ap.

aqua- (prefix) = water.

aquabot = an aquatic robot or autonomous underwater vehicle used in oceanographic research.

aquaculture = the artificial or controlled culture of aquatic organisms, including stripping and fertilisation of eggs and raising of young to a certain size for release or marketing. Also spelled aquiculture, but this also means hydroponics.

aquafeed = commercial fish food.

aqualung = a self-contained, portable underwater breathing apparatus for divers. Comprises a cylinder(s) of compressed air strapped to the back feeding that air to the diver through a mask or mouthpiece.

aquamarsh = a water body almost completely covered with emergent an floating aquatic vegetation.

aquanaut = an underwater researcher, explorer or swimmer. Also called oceanaut.

aquaria = plural of aquarium.

aquariology = the care, maintenance and breeding of captive aquatic animals. Includes design of displays and veterinary medicine and pathology.

aquarist = a person who keeps fish or other organisms in an aquarium. Sometimes used for pondkeeper and fishkeeper.

aquaristics = the study of aquarium organisms on a scientific basis.

aquarium (plural aquaria) = an artificial tank with glass or plastic sides allowing the fish to be viewed; also a large facility with many aquaria, often open to the public.

aquarium collecting = use of small-meshed nets and traps for collecting fish for display in aquaria.

aquarium furniture = a general term for castles, mermaids, pirate ships, treasure chests and other dubious items made for decorating aquaria.

aquarium material = species bred in an aquarium rather than collected from the wild.

aquarium salt = an additive-free salt used in treatment of disease in freshwater aquarium fishes or added in very small quantities of freshwater aquaria where it is beneficial to certain species. Not the same as marine salt, a preparation used to imitate sea water for marine aquaria.

aquariums = sometimes used as a plural for aquarium.

aquascaping = arrangement of plants in an aquarium in an artistic fashion, often with rocks, and including the necessary equipment to maintain the environment.

aquasperm = the morphologically simple sperm of externally fertilizing teleosts. Typically having a round head without an acrosome, a single, generally unadorned flagellum and a short mid-piece with a prominent cytoplasmic canal.

aquatic = living in or near water or pertaining to water.

aquatic chicken = a slang term for Tilapia spp., cichlids used extensively for fish farming.

aquatic surface respiration = absorption of oxygen through the gills from the thin (few millimetres), oxygen-rich surface layer of a water body. Used by fish in hypoxic conditions.

aquatic tongue = the use of water currents in the mouth by some fishes, acting as a hydraulic tongue to manipulate food.

aquaticolous = living in water or aquatic vegetation.

aquatoria = water world or habitat.

aquatron = a facility with very large tanks for fish or other aquatic organism studies.

aqueduct of Sylvius = a posterior channel joining the third and fourth ventricle in the brain.

aqui- (prefix) = relating to water.

aquifer = a water bearing geological formation. Springs and wells depend on aquifers for water. Described as artesian (confined) or water table (unconfined). May contain "cave" fishes.

aquiculture = see aquaculture.

aragonite = calcium carbonate skeletons of reef corals and some shells sold as a substrate for marine aquaria. Has high levels of calcium and strontium carbonate.

arbalete = an underwater spear gun used for catching fish.

arbitrary = used of scientific name lacking formal derivation with regard to etymology, e.g. an arbitrary combination of letters, or an etymologically incorrect gender assigned to a name.

arbor = the centre part of a fly reel (spool) where backing and line are wound; usually indicates the size of the spool with large arbors useful in fly fishing to prevent the line from curling.

arbor knot = a knot used to tie line to the reel spool. Has a strength of 60%. The main line is wrapped around the spool, a knot tied across it and a knot tied near the end of the line. a steady pull on the line tightens the first knot against the spool and is locked by the second knot. Various websites have animated steps showing how to tie this knot.

arborescent = treelike.

arborescent organ = 1) a branched, accessory, vascular structure in the gill chamber, e.g. in Clarias gariepinnis.

arborescent organ = 2) dendritic organ (a small arborescent organ found between the anus and the anal fin in certain Plotosidae (e.g. Plotosus, Cnidoglanis and Euristhmus). Organ with two main cell types, those with parallel groups of cytoplasmic tubules and many mitochondria, and clear cells with a network of cytoplasmic tubules. May have an osmoregulatory function).

arboriform = form of a tree, branching.

Arbroath smokie = a whole smoked haddock with its backbone retained, usually gutted and headed (Scotland). Initially cold smoked for several hours, then hot smoked. Also known as Auchmithie cure, close fish, pinwiddie.

arch dam = a curved masonry or concrete dam with a convex upriver shape. The water pressure is transferred by the arch to abutments.

arch- = prefix meaning ultimate beginning.

arch-centra = vertebral centra formed by the growth of the arcualia around the notochord external to the chordal sheath and which fuse to form annual segments which become biconcave centra. Found in Teleostei.

archangel Raphael = usually depicted in Christian art by a pilgrim’s staff, or carrying a fish, in allusion to his aiding Tobias (see Tobit) to capture the fish which performed the miraculous cure of his father’s eyesight.

archetype = a hypothetical ancestor constructed by elimination of specialised characters.

archi- (prefix) = first, primitive, original, ancestral.

archibenthic = the waters on the slope beyond the outer edge of the continental shelf at depths between 200-400 and 1000-1100 metres or below the 4°C isotherm.

archicercal = proterocercal (the type of tail fin primitively symmetrical, both internally and externally, and hence one which has not undergone reduction or modification of the original form, e.g. in Petromyzontiformes).

archinephros = the primitive kidney extending the whole length of the body cavity. Found only in embryonic Myxini.

archipelago = a group of islands or an expanse of water with scattered islands.

archipterygium = the primitive lobe-like paired fin. Generally applied to the biserial fin or lobe-fin, e.g. in Crossopterygii, or to the lobe fin of some Elasmobranchii, e.g. Pleurocanthus.

archival tag = an implanted fish tag that detects and records several environmental variables, e.g. water temperature, over time or internal variables, e.g. body temperature.

arciform = bow-shaped.

arcocentrum = the cartilaginous arch and its base in the vertebrae of Elasmobranchii. Also used in Pycnodont Actinopterygii (Poyato-Ariza and Wenz, 2002).

Arctic cities = dense gatherings of trawlers fishing demersally in Arctic waters.

arcualia = plural of arcualium.

arcualium (plural arcualia) = an embryonic cartilaginous element from which the vertebrae form. There are primitively two pairs of endoskeletal elements in each metamere and on each side of the notochord, the interdorsals and basidorsals. In the gnathostomes (jawed fishes) there are two additional pairs ventrally to the notochord, the interventrals and basiventrals. All these elements are called arcualia and can fuse to a notochordal calcification, the centrum. Arcualia and centrum make a vertebra.

arcuate = in a smooth arc, not straight or interrupted.

arcus hæmales = plural of arcus hæmalis.

arcus hæmalis (plural arcus hæmales) = haemal arch (the arch which encloses the caudal vein and dorsal aorta and is found on the ventral surface of the more posterior (caudal) vertebrae. In Acipenseridae it is continuous but interrupted in Actinopterygii).

arcus hyoidei = plural of arcus hyoideus.

arcus hyoideus (plural arcus hyoidei) = hyoid arch (the arch lying between the gill arches and jaws, with which it is believed homologous and which helps support the floor of the mouth cavity. Composed in teleostomes of the following paired endoskeleton elements: hyomandibula, symplectic, interhyal, ceratohyal and one or two hypohyals which articulate with the basihyal. The prefixes epi-, cerato- and hypo- should not be interpreted as indicating correspondence with branchial elements bearing the same prefix. Posterohyal (epihyal), anterohyal (ceratohyal), dorosohyal (dorsal hypohyal) and ventrohyal (ventral hypohyal) have been coined to avoid this confusion. Some authors eschew the term epihyal and employ for the epihyal and ceratohyal, posterior and anterior or proximal and distal ceratohyal).

arcus inferiores = plural of arcus inferioris.

arcus inferioris (plural arcus inferiores) = haemal arch (the arch which encloses the caudal vein and dorsal aorta and is found on the ventral surface of the more posterior (caudal) vertebrae. In Acipenseridae it is continuous but interrupted in Actinopterygii).

arcus mandibulares = plural of arcus mandibularis.

arcus mandibularis (plural arcus mandibulares) = mandibular arch (the cartilages and bones of the visceral skeleton forming the jaws. The upper jaw elements are the palatoquadrate or pterygoquadrate cartilages, the lower jaw ones Meckel's cartilages and the angular. This is the basic jaw, the primary mandibles, which have several ossification centres in bony fishes. Teeth and dermal bones are later evolutionary additions and are called the secondary mandibles).

arcus neurales = plural of arcus neuralis.

arcus neuralis (plural arcus neurales) = neural arch (the arch enclosing the spinal cord on the dorsal surface of the vertebrae. Generally continuous in Chondrostei but separate arches in Teleostei give more flexibility. Acipenseridae have two canals, the upper for the longitudinal ligament and the one under it for the sp