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Glossary of fish terms
This page lists many of the fish terms used on the site. Much of the list is copied from McCulloch's 1934 publication 'The Fishes and Fish-Like Animals of New South Wales. Ed 3. With Supplement by G. P. Whitley. Royal Zoological Society of NSW. pp i-XXvi, 1-104, Pl i-xliii'.
| A | |
| Abdomen | belly |
| Abdominal | pertaining to the belly |
| Actinosts | a series of bones at the base of the pectoral rays |
| Acuminate | tapering gradually to a point |
| Acute | sharp, pointed |
| Adipose | shy or fatty. Often applied to small rayless fins and to eyelids |
| Adipose fin | a small fleshy fin which lacks fin rays. See adipose. |
| Adnate | joined together |
| Adpressed | pressed against the body |
| Aestivate | to be inactive during warm dry periods |
| Airbladder | see swimbladder |
| Alimentary canal | the passage through which food passes, starting at the mouth and ending at the anus |
| Anal | pertaining to the anus or anal fin |
| Anal fin | the fin on the median line behind the vent |
| Anal fin origin | the most anterior point of the anal fin base |
| Ankylosed | grown firmly together |
| Anterior | relating to the front portion |
| Antrose | turned forward |
| Anus | the external opening of the intestine, the vent |
| Approximate | placed close together |
| Asperity | roughness of surface |
| Asymetrical | without symmetry |
| Attenuate | tapering to a point, usually in reference to a tail |
| Axillary | pertaining to the axilla or upper angle of the pectoral fin |
| Axillary process | an enlarged, pointed scale projecting from the insertion of the pectoral or pelvic fin.) |
| B | |
| Barbel | an elongated fleshy projection, usually about the head |
| Basal | pertaining to the base, at the base |
| Base | the part of a projection, (commonly a fin), which is connected to the body |
| Bathypelagic | living at a depth between 1000 m and 4000 m, but well off the bottom |
| Benthic | bottom-dwelling, living on the sea bed |
| Benthopelagic | pertaining to fishes that swim just above the seabed at depths below about 200 m (the edge of the continental shelf) |
| Bicuspid | having two cusps or points |
| Bifid | cleft in two |
| Bifurcate | forked, or divided into two parts or branches |
| Branchial | pertaining to the gills |
| Branchial aperture | the gill opening |
| Branchiostegals, Branchiostegal ray(s) | bony rays supporting the gill membranes behind the lower jaw |
| Bristle | a stiff hair-like projection |
| Buckler | a bony shield |
| Bycatch | species other than the target species that are caught incidentally in a trawl |
| C | |
| Canines | conical teeth which are longer than other teeth |
| Caniniform | shaped like a canine tooth, conical in form |
| Carapace | a horny or bony covering encasing the body |
| Carinate | keeled, having a ridge along the middle line |
| Cartilage | Cartilaginous: gristle, gristly |
| Caruncle | a fleshy outgrowth |
| Caudal | pertaining to the tail |
| Caudal fin | the tail fin |
| Caudal peduncle | the region of the body between the end of the anal fin and the base of the caudal fin |
| Ciliated | fringed with eyelash-like projections |
| Cirri | small, thin appendages, often subdivided into branches. |
| Cirrus | singular of cirri (see above) |
| Claspers | the external reproductive organs of male sharks, rays and chimaeras |
| Coalesced | grown together |
| Compressed | flattened laterally |
| Confluent | joined together |
| Conical | cone shaped, with a cylindrical base and a pointed tip |
| Corselet | a scaly covering behind the pectorals of some fishes |
| Continental shelf | the region of the seabed extending from the coast down to a depth of around 200 m |
| Continental slope | the region of the seabed that slopes down from a depth of around 200 m (the edge of the continental shelf) to around 2000 m |
| Countershading | body colouration which is dark above and lighter below |
| Cranium, Cranial | the skull, pertaining to the skull |
| Crenulate | having the edge slightly scalloped |
| Cusp | a point or projection on a tooth |
| Cutaneous | pertaining to the skin |
| Ctenoid | rough-edged |
| Cycloid | smooth-edged |
| D | |
| Deciduous | easily removed / rubbed off, temporary, falling off |
| Demersal | living on or near the sea bed |
| Dendritic | resembling a tree or shrub |
| Denature | the "unfolding" of a protein resulting in a lessening of its biological properties. In the case of some fish toxins, denaturing with hot water can lessen painful symptoms. |
| Dentate | with tooth-like projections |
| Denticle, denticulate | a little tooth, having an edge with small projecting teeth, the placoid scales of cartilaginous fishes |
| Depressed | flattened from top to bottom |
| Dermal | pertaining to the skin |
| Dewlap | a fold of loose skin |
| Disc | the flattened head and body of various fishes such as stingrays, which also commonly includes the pectoral and ventral fins |
| Distal | remote from the point of attachment |
| Dorsal | pertaining to the back |
| Dorsum | the upper (dorsal) surface of the head or body |
| Dorsal fin | the fin on a fish's back |
Dorsal fin origin |
the most anterior point of the dorsal fin base |
| E | |
| Elasmobranchs | cartilaginous fishes - sharks, rays and allies |
| Electrocyte | a cell that generates electricity |
| Elongate | extended, drawn out |
| Emarginate | with the margin slightly hollowed |
| Endemic | restricted to a particular region, for example endemic to Australia |
| Entire | with a smooth margin |
| Epibenthic | referring to organisms living on the bottom surface |
| Epipelagic | referring to organisms living in the region between the surface and 200 m depth |
| Erectile | capable of being raised or erected, often referring to spines |
| Esca | the lure or "bait" on the end of the illicium of some anglerfishes and relatives |
| Estuarine | living in estuaries |
| Etymology | The study of word origins and derivation. |
| F | |
| Falcate | scythe-shaped, long, narrow, and curved |
| Falciform | curved like a scythe |
| Filament | a slender or thread-like structure |
| Filiform | thread-like |
| Fimbriate | fringed at the margin |
| Finlet | a small fin, positioned behind the dorsal or anal fins, that is supported by a ray or rays |
| Fluviatile | living in rivers |
| Fork length | The length of a fish as measured from the tip of the snout to the fork of the caudal fin. Often used for angling species. |
| Free rear tips (of fins) | the posterior tip of the fin that is closest to the most posterior point of the fin base |
| Frontal ridge | a ridge running along the top of the head along the midline |
| Furcate | forked |
| Fusiform | tapering towards both ends |
| G | |
| Gill arches | the bony arches to which the gills are attached |
| Gill cover | or bony flap that covers the gills, the operculum |
| Gill filaments | a series of projections along the posterior edge of the gill arch, the site of gas exchange |
| Gill membranes | membranes covering the gill openings, attached to the branchiostegals |
| Gill opening | opening behind each operculum, leading to the gills |
| Gill rakers | a series of appendages along the anterior edges of the gill arches |
| Gills, Branchiae | organs for breathing the air contained in water |
| Glossohyal | the tongue bone |
| Gonads | the sexual organs which produce eggs or sperm |
| Gonopodium | a modification of the anal fin of some male fishes, that is used to transfer reproductive products to the female |
| Gravid | sexually ripe |
| Gular region | pertaining to the region behind the chin and between the sides of the lower jaw |
| H | |
| Heart | the large muscle which pumps blood around the circulatory system |
| Head length | the distance from the tip of the snout (or upper lip) to the most posterior point of the opercular margin |
| Herbivore | an animal that eats plants |
| Heterocercal | pertaining to the shape of a tail with a long upper lobe and a shorter lower lobe |
| Homology | similarity of features based on common evolutionary descent |
| Hyperostosis | a condition resulting in enlargement of areas of bone. |
| Hyaline | translucent or transparent |
| Hypural joint | the joint between the caudal fin and the last of the vertebrae |
| Hypural plate | the flattened bony plate at the posterior end of the vertebral column, formed from parts of the posterior vertebrae. |
| I | |
| Ichthyocide | a substance used to kill (and usually collect) fishes |
| Ichthyoplankton | fish eggs and larvae |
| Illicium | a "fishing rod-like" appendage on the head, usually a modified dorsal fin spine |
| Imbricate | overlapping, like the shingles on a roof |
| Incised | with a notched margin (often referring to fin membranes) |
| Incisors | the front or cutting teeth |
| Inferior | pertaining to the lower side (usually of the head) |
| Interdorsal | between the dorsal fins |
| Interorbital | the space between the orbits |
| Intromittent organ | a structure to facilitate sperm transfer in some internally fertilizating species |
| Iris lappet | a fleshy flap or lobe-like structure in the eye, short and rounded, simple or multiply branched. |
| Isthmus | the fleshy projection of the body separating the gill openings |
| J | |
| Jugular | pertaining to the throat |
| Junior synonym | where more than one scientific name has been used to describe a species, all but the oldest name (the senior synonym) are junior synonyms. |
| Juxtaposed | placed near together |
| K | |
| Kidneys | organs involved in excretion and regulation of water balance |
| L | |
| Lanceolate | spear-shaped, gradually tapering toward the extremity |
| Labial | pertaining to the lips |
| Labial furrows | shallow grooves around the lips |
| Labial papillae | small fleshy projections around the lips |
| Lateral | at or toward the side |
| Lateral line | a series of muciferous tubes forming a raised line along the side of the body |
| Liver | a digestive and storage organ |
| Longitudinal series (scales) | the number of scale rows above the lateral line from the first pored lateral line scale to the caudal fin base. |
| Lunate | shaped like a crescent moon, with long upper and lower lobes |
| M | |
| Mandible | the lower jaw |
| Maxilla, Maxillary | the upper jaw, or pertaining thereto |
| Maxillae, Maxillaries | the hindmost bones of the upper jaw; preceded by the premaxillaries |
| Median, medially | pertaining to the middle |
| Median fins | fins located on the median line of the fish; the dorsal, anal and caudal fins |
| Mediolateral | between the middle and the sides |
| Mesocoracoid | a bone of the pectoral arch or shoulder girdle |
| Mesopelagic | refers to the region of the open ocean between 200 m and 1000 m in depth |
| Mesopelagic fishes | fishes that live in the mesopelagic zone |
| Midwater | the middle stratum of water, well below the surface and well above the seabed. See also mesopelagic. |
| Midwater fishes | fishes that live in the midwater |
| Molars | blunt and rounded grinding teeth |
| Morphology | form and structure of an organism |
| Muciferous | producing or containing mucous or slime |
| Myotomes | blocks of lateral trunk muscles |
| N | |
| Nape | upper surface of the body behind the head and before the dorsal fin |
| Nasal | pertaining to the nostrils |
| Nasoral | between the nostrils and mouth |
| Nictitating membrane | an inner eyelid |
| Notochord | a rudimentary of embryonic spinal column |
| Nuchal | pertaining to the nape |
| O | |
| Obsolete | faintly marked, scarcely evident |
| Obtuse | blunt |
| Occipital | pertaining to the posterior part of the skull |
| Ocellus | an eye-like spot |
| Ocular | pertaining to the eye |
| Oesophagus | the gullet |
| Olfactory organs | the organs used for smelling, commonly beneath the nostrils |
| Omnivore | an animal with a diet that consists of both plant and animal material |
| Opercule, operculum | the bony flap that covers the gills |
| Opercular | pertaining to the operculum |
| Opercular spine | spine projecting from the operculum |
| Orbit | the eye socket |
| Origin | the most anterior point of a fin base |
| Osseus | bony |
| Ossicle | A bony plate. As seen on the clavus of Sunfishes. |
| Osteological | pertaining to bones |
| Osteology | the study of bones |
| Otolith | Calcareous structures in the ear capsules of bony fishes. Also known as ear bones. |
| Ovate | egg-shaped |
| Oviparous | a species that produces eggs that are hatched outside of the body of the female. |
| P | |
| Palate | the roof of the mouth |
| Palatines | the bones on each side of the palate |
| Papilla (papillae) | a small fleshy projection(s) |
| Papillose | covered with papillae |
| Pectoral | pertaining to the breast |
| Pectoral fins | the anterior or uppermost of the paired fins, which correspond to the anterior limbs of the higher vertebrates |
| Pectoral girdle | the bones to which the pectoral fin is attached |
| Peduncle | usualy referred to as the caudal peduncle, the region of the body between the end of the anal fin and the base of the caudal fin |
| Pelagic | living on or in the open seas |
| Pelvic girdle | the bones to which the ventral fins are attached |
| Pelvic fins | paired fins behind or below the pectoral fins |
| Peritoneum | the membrane lining the abdominal cavity |
| Pharyngeal bones | bones behind the gills in the oesophagus or gullet |
| Pharyngeal teeth | teeth within the pharynx |
| Pharynx | the back part of the throat, into which the gill slits open |
| Photophore | a circular light-producing organ on the surface of a fish |
| Piscivorous | an organism that feeds upon fishes |
| Planktivore | an animal with a diet that consists mainly of plankton |
| Posterior | towards the hind end of the fish |
| Postorbital | behind the eye |
| Precaudal | anterior to the tail portion |
| Prehensile | adapted for holding, such as the tail of a seahorse |
| Premaxillaries | two bones forming the front portion of the upper jaw |
| Preocular spine | spine positioned above and in front of the eye |
| Preopercle, preoperculum | the bone between the cheek and the gill cover |
| Preopercular spine | spine projecting from the preopercule (see preopercle) |
| Preorbital | the area under and in front of the eyes |
| Protractile | capable of extending forward |
| Protrusible | capable of extending forward, often referring to the jaws of fishes |
| Proximal | nearest |
| Pseudobranchiae | small gills developed on the inner side of the gill cover |
| Pseudoclasper | stiff ossified lobes or prongs in the tip of the intromittent organ |
| Pterygiophore | an internal cartilage or bone that supports a median fin ray or spine |
| Pyloric caecae | finger-like pouches connected with the alimentary canal (the gut) |
| R | |
| Ramus | one branch or one half of the jaw |
| Ray | a jointed rod which supports a fin |
| Retrose | turned backward |
| Rostrum | a projecting snout or beak |
| Rugose | rough |
| S | |
| Scalation | pertains to the pattern/arrangement/presence of scales |
| Scute | any external horny or bony plate |
| Senior synonym | the oldest name used to describe a species |
| Serrate | notched like a saw |
| Setae | bristles or hairs |
| Sexual dimorphism | differences in physical appearance between the sexes |
| Soft dorsal | the posterior part of the dorsal fin which is composed of jointed rays |
| Spatulate | shovel-like; having a broad, flat and rounded shape |
| Spine | a sharp projecting point; an unjointed support in the anterior portions of the dorsal and anal fins |
| Spinous, spiniform, spinate | spine-like or composed of spines |
| Spinous dorsal | the anterior part of the dorsal fin supported by spines |
| Spiracles | respiratory openings behind the eyes in sharks and rays |
| Standard length (SL) | the length of a fish measured from the tip of the snout to the posterior extremity of the hypurals, the expanded bones at the end of the backbone that support the caudal fin |
| Sub- (a prefix) | less than, somewhat, not quite, under |
| Submarginal | almost at the edge |
| Suborbital | below the eye |
| Superior | above or on the upper surface |
| Supracleithrum | the bone forming a connection between the back of the skull and the pectoral girdle |
| Supralateral | above the side |
| Supramaxillary | a supplemental bone lying along the upper edge of the maxillary |
| Supraocular | positioned above the eye |
| Supraorbital | above the eye |
| Supraorbital tentacle | a flap or filament of skin positioned above the eye |
| Suprascapular | a bone uniting the shoulder girdle with the skull |
| Suture | the line of union of two bones or plates |
| Symphysis | point of junction of the two sides of the jaw Symmetrical: similarly arranged on both sides |
| Synonym | a different word having the same or a similar meaning |
| Swimbladder | a sac filled with gas, lying beneath the backbone |
| Symbiosis | used to describe any association between two organisms. From a Greek word meaning 'living together'. |
| Symphysis | the junction of two bones of body elements, often used to describe the middle point at the front of the jaws |
| Synonym | one of two or more names that have been used to describe the same species |
| Systematics | The study of the evolutionary and genetic relationships between organisms. |
| T | |
| Taxonomy | the science of classifying organisms |
| Teleost | a large group containing most of the bony fishes |
| Terminal | at the end |
| Tessellated | marked with little checks or squares, like tiles |
| Thoracic | pertaining to the chest |
| Thorax | the chest region, just behind the head |
| Total length | the length from the tip of the snout to the tip of the tail |
| Transverse | crosswise |
| Trilobate | with three lobes |
| Tricuspid | with three cusps or points |
| Truncate | terminating abruptly, as if cut off square |
| Trunk | the region of a fish between the head and tail, or the last gill slit and vent |
| Tubercle | a small, usually hard excrescence or lump |
| Tubiform, Tubuliform | resembling a tube |
| Type locality | the location from which the type specimen was collected eg Sydney Harbour |
| U | |
| Undulated | waved |
| Uniform (as applied to colouration) | of one colour |
| Urogenital papilla | a papilla through which the urinary waste and gametes leave the body |
| V | |
| Vent | the external opening of the alimentary canal, the anus |
| Ventral | pertaining to the abdominal or lower surface |
| Ventral fins | paired fins behind or below the pectoral fins |
| Vertebrae | the bones of the spinal column |
| Vertebrate | an animal with a backbone |
| Vertical fins | fins on the median line of the body; the dorsal, anal, and caudal fins |
| Vestigial | reduced, or very poorly developed |
| Villiform teeth | small, slender teeth forming velvety bands |
| Viviparous | a species that gives birth to live young. The developing embryo is nourished within the body of the female. |
| Vomer | a bone forming the front part of the roof of the mouth |
| Vomerine teeth | teeth on the vomer (see above) |
| X | |
| Xanthism (xanthochroism) | An unusual colour variety in which the normal colouration of a fish is largely replaced by yellow pigments. |
| Further reading: | |
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