|Fish Identification: Find Order|
|46 orders of ray-finned fishes|
Tetraodontiformes - puffers and filefishes
No parietals, nasals, or infraorbitals, and usually no lower ribs; posttemporal, if present, simple and fused with pterotic of skull; hyomandibular and palatine firmly attached with premaxilla; scales usually modified as spines, shields, or plates; lateral line present or absent, sometimes multiple; swim bladder present except in molids; 16-30 vertebrae.
Pleuronectiformes - flatfishes
Adults not bilaterally symmetrical, with one eye migrating to the other side of the cranium; dorsal and anal fins with long bases, dorsal fin base overlapping at least the neurocranium except in Psettodes; body highly compressed, somewhat rounded on eyed side and flat on blind side; eyes can protrude above body surface allowing fish to see when buried in the substrate; usually six or seven branchiostegal rays, rarely eight; body cavity small; adults almost always without swim bladder; scales cycloid, ctenoid, or tuberculate. About four species probably occur in freshwater, while another 20 species that are normally marine occasionally enter freshwater.
Perciformes - perch-likes
Largest order of fishes. Most families in many suborders are not currently definable in terms of shared derived characters and thus may not be monophyletic. Most perciforms are marine shore fishes, while about 2,000 species (e.g. cichlids) normally occur only in freshwater, and about 2,200 species occur in freshwater for at least part of their life history.
Scorpaeniformes - scorpionfishes and flatheads
Contains the "mail-cheeked" fishes, distinguished by the suborbital stay, a posterior extension of the third infraorbital bone (counting the lachrymal), which extends across the cheek to the preoperculum and is usually firmly attached to that bone. Head and body tend to be spiny or have bony plates; pectoral fin usually rounded, membranes between lower rays often incised; caudal fin usually rounded (occasionally truncate, rarely forked).
Synbranchiformes - spiny eels
Body elongate; pelvic fins absent; gill openings confined to lower half of body; ectopterygoid enlarged; mesopterygoid reduced or absent; premaxillary nonprotrusible and without ascending process. All species except three occur in freshwater.
Syngnathiformes - pipefishes and seahorses
Body elongate and encased in a series of bony rings; mouth small, at end of tube-shaped snout (except in the "finless" pipefish Bulbonaricus, whose adults lack even a short tubiform snout); pelvic fins, when present, abdominal; upper jaw not protractile; lachrymal usually present, other circumorbital bones usually absent; ribs absent; anterior 3-6 vertebrae elongate; aglomerular kidney in at least some.
Gasterosteiformes - sticklebacks and seamoths
Pelvic girdle never attached directly to the cleithra; supramaxillary, orbitosphenoid, and basisphenoid absent; postcleithrum a single bone or absent; branchiostegal rays 1-5; body often with armor of dermal plates; mouth usually small. About 19 species are restricted to freshwater, and another 40 species are found in brackish water (some being variously diadromous or at lest able to commonly enter freshwater and marine water).
Zeiformes - dories
Pelvic fin with or without a spine and 5-10 soft rays; caudal fin usually with 11 branched rays (13 in grammicolepidids); dorsal fin spines 5-10; anal fin spines 0-4; soft rays of dorsal, anal, and pectoral fins not branched; body usually thin and deep; jaws usually greatly distensible; no orbitosphenoid; simple posttemporal fused to skull; swim bladder present; branchiostegal rays 5-8; vertebrae 21-46. Caproids have the lowest number of vertebrae and grammicolepidids the highest. All species are marine, most are deep sea.
Cetomimiformes - whalefishes
Complete loss of fin spines. The whalefishes have a whale-shaped body; mouth very large and stomach highly distensible; eyes well developed to degenerate; latera line made up of enormous hollow tubes; luminous tissue on body; dorsal and anal fins far back on body and opposite one another; no swim bladder; orbitosphenoid absent; supramaxilla absent or reduced; color usually orange and red on a black body.
Beryciformes - sawbellies
Orbitosphenoid present; two supramaxillae in Berycidae and Holocentridae; subocular shelf present (may be reduced); pelvic fins usually with more than five soft rays; 16 or 17 branched caudal fin rays (or 18 or 19 principal rays); maxillae partially included in gape in some. All species share a modification of the anterior part of the supraorbital and infraorbital sensory canals, called "Jakubowski's organ".
Stephanoberyciformes - pricklefishes, bigscales and gibberfishes
Body usually roundish; palate toothless; skull bones, in general, exceptionally thin; orbitosphenoid absent (except in Hispidoberyx; subocular shelf absent; supramaxilla absent or reduced.
Beloniformes - needle fishes
Interarcual cartilage (connects the epibranchial bone of the first gill arch with the infrapharyngobranchial of the second gill arch) small or absent; small second and third epibranchials; interhyal absent; lower caudal fin lobe with more principal rays than the upper lobe. Presence of a fixed or nonprotrusible upper jaw.
Cyprinodontiformes - rivulines, killifishes and live bearers
Monophyly of this order is recognized on the basis of several derived characters: e.g., caudal fin symmetrical, supported internally by one epural; first pleural rib on second vertebrae rather than third; primitively, low-set pectoral girdle with a scalelike postcleithrum; an alveolar arm of the premaxillae; extended developmental period. In addition, they possess the following characters: lateral line canal and pores chiefly on head, lateral line represented on body only by pitted scales; narial opening paired; branchiostegal rays 3-7; pelvic fins and girdle present or absent; upper jaw bordered by premaxilla only, protrusible; vomer usually present and supracleithrum always present; metapterygoid usually absent and ectopterygoid always absent; parietals present or absent; vertebrae 24-54. Marked sexual dimorphism with the males often brightly colored.
Atheriniformes - silversides
Usually two dorsal fins, the first, if present, with flexible spines; anal fin usually preceded by a spine; lateral line absent or very weak; branchiostegal rays 4-7; narial openings paired; pelvic fins abdominal, subadominal, or thoracic in position (essentially absent in female phallostethids and highly modified in male phallostethids); parietals usually present.
Gobiesociformes - clingfishes
Pelvic fins modified into a thoracic sucking disc (permitting fish to adhere to substrate), with underlying pelvic bones specialized for supporting disc (pelvic skeleton highly reduced in Alabes; each pelvic fin with one small spine and four soft rays (rarely five); single dorsal fin without spines; head and body scaleless; branchiostegal rays 5-7 (three in Alabes); no circumorbital bones posterior to the lachrymal; articular process of premaxilla either fused with ascending process or absent; basibranchials one and two probably absent; supracleithrum with concave process that articulates with condyle oncleithrum (not known from other fishes); basisphenoid and orbitosphenoid absent; genital papilla behind anus; three or three and half gills; hypurals fused into a single plate; no swim bladder. The following characters apply to all species except Alabes: scapula and four pectoral radials and 16-31 pectoral fin rays; usually two postcleithra (rarely one); either common gill opening or separate opening on each side; pleural ribs attached to the epineural (?) ribs (an opposite relationship to that found in most fish); total caudal fin rays 16-27 (8-14 articulating on hypural fan); vertebrae 25-54 (11-20 + 13-33). Maximum length normally 7 cm.
Lophiiformes - anglerfishes
First ray of spinous dorsal, if present, on head and transformed into illicium (line) and esca (bait), a device for attracting prey to mouth; pelvic fins, if present, in front of pectorals, with one spine and four (rarely) or five soft rays; gill opening small tubelike, at or behind (rarely partly in front of) pectoral fin base; five or six branchiostegal rays; no ribs; pectoral radials 2-5, narrow and elongate; first vertebra fused to skull; swim bladder, when present, physoclistous.
Batrachoidiformes - toadfishes
Body usually scaleless (small cycloid scales in some); head large with eyes more dorsal than lateral; mouth large and bordered by premaxilla and maxilla; pore (foramen) in axil of pectoral fin in some; pelvic fins jugular (in front of pectorals), with one spine and two or three soft rays; three pairs of gills; gill membrane broadly joined to isthmus; branchiostegal rays six; four or five pectoral radials; swim bladder present; upper hypurals with peculiar intervertebrallike basal articulation with rest of caudal skeleton; no ribs, epiotics, or intercalars; no pyloric caeca.
Ophidiiformes - cusk eels
Pelvic fins when present, inserted at level of preopercle or farther anterior (mental or jugular), zero to two soft rays in each, and occasionally with a spine; base of dorsal and anal fins long, extending to and usually joined with caudal fin; nostrils paired on each side; dorsal and anal fin pterygiophores more numerous than adjacent vertebrae (the ratio being about 1.8:1).
Gadiformes - cods
Pelvic fins, when present, inserted below or in front of pectorals (thoracic or jugular, rarely behind in Macrouridae) with up to 11 rays; no true spines in the fins; most with long dorsal and anal fins; scales usually cycloid, rarely ctenoid; premaxilla forms the entire margin of upper jaw, protractile in some; ectopterygoid toothless; orbitosphenoid and basisphenoid absent; branchiostegal rays 6-8; posterior vertebral reduction results in posterior dorsal and anal pterygiophores exceeding the number of caudal vertebrae; swim bladder without pneumatic duct (the swim bladder is absent in Melanonus and Squalogadus).
Percopsiformes - trout-perches, pirate perches and cavef
Premaxilla nonprotractile; ectopterygoid and palatine with teeth; pelvic fins, if present, behind pectorals and with 3-8 soft rays; spines (normally weak) usually present in dorsal fin; many species with ctenoid scales; six branchiostegal rays; 16 branched caudal rays; orbitosphenoid, basiphenoid, and suborbital shelf absent; vertebrae 28-35.
Polymixiiformes - beardfishes
Moderately elongate and compressed. A pair of barbels on hyoid. Continuous dorsal fin; 4-6 spines, 26-38 soft rays. Anal fin 4 short spines, 13-17 soft rays. Subabdominal pelvic fin; 1 spinelike ray, 6 soft rays. Caudal fin 16 branched rays. Scales in lateral line about 33-38. Banchiostegal 4 rays. Gillrakers 11-21. Supramaxillae 2. Epurals 3. Subocular shelf, ortbitosphenoid, and basisphenoid present. Vertebrae usually 29 or 30. Maximum length is 38 cm. Usually found in depths between 180 and 640 m.
Lampriformes - velifers, tube-eyes and ribbonfishes
No true spines in fins; premaxilla excludes maxilla from gape; unique type of protrusible upper jaw (maxilla, instead of being ligamentously attached to the ethmoid and palatine, slides in and out with the highly protractile premaxilla in at least the first four suborders); pelvic fins with 0-17 rays; swim bladder, when present, physoclistous; orbitosphenoid present in some.
Myctophiformes - lanternfishes
Head and body compressed; eye lateral (dorsolateral in the myctophid Hierops); mouth usually large and terminal; adipose fin present; usually 8 pelvic fin rays; usually 7-11 branchiostegal rays. All are deep-sea pelagic and benthopelagic fishes.
Aulopiformes - grinners
Second pharyngobranchial greatly elongated posterolaterally, extending away from third pharyngobranchial, with elongated uncinate process of second epibranchial contacting third pharyngobranchial, and third pharyngobranchial lacking cartilaginous condyle for articulation of second epibranchial.
Ateleopodiformes - jellynose fishes
Caudal fin reduced, united with the long anal fin; pelvic fin of adults with single ray on throat (young specimens and Guentherus gave several rays, and the pelvics of the latter are behind the pectorals); dorsal fin with 3-13 rays; skeleton largely cartilaginous; snout bilbous; branchiostegal rays 7. Maximum length about 2 m. Marine species.
Stomiiformes - lightfishes and dragonfishes
Luminescent organs (photophores) present; chin barbel present in some; premaxilla and maxilla in gape of mouth - both have teeth; mouth extending past eye in most; scales, if present, cycloid and easily lost; pectoral, dorsal, or adipose fins absent in some; ventral adipose fin present in some; pelvic fin rays 4-9; branchiostegal rays 5-24. Color in most is dark brown or black; some are silvery (primarily some Gonostomatoidei). Most tropical to temperate; many are deep-sea.
Salmoniformes - salmons
Deep posterior myodome with eye musculature passing through and attaching to trunk muscles; adipose fin present; mesocoracoid present; gill membranes extending far forward, free from isthmus; pelvic axillary process present; last three vertebrae turned up; 11-210 pyloric caeca; 7-20 branchiostegal rays; vertebrae 50-75; tetraploid karyotype; parr marks in young of most species. Maximum length up to 1.5 m. This order has high value in sport and commercial fisheries.
Osmeriformes - smelts
Maxilla included in gape of mouth (the toothless maxilla is excluded from the gape in Protroctes and Lovettia and almost so in Aplochiton; adipose fin present or absent; radii absent on scales; loss of basisphenoid and orbitosphenoid bones. Osmeriforms spawn in freshwater except the Argentinoidei, Osmerus eperlanus, and perhaps one or two salangids.
Esociformes - pikes and mudminnows
Maxilla toothless but in gape of mouth; no adipose fin; dorsal and anal fins located posteriorly; no breeding tubercules; no pyloric caeca; no mesocoracoid.
Gymnotiformes - knifefishes
Body eel-like (compressed or rounded); pelvic girdle and fins absent; dorsal fin absent; anal fin extremely long (more than 140 rays and extending from near pectoral fin origin to near tip of body) and employed in forward and backward movements; caudal fin absent or greatly reduced; restricted gill openings; anal opening under head or pectorals; basal pterygiophores to anal fin with only one section (radial) and a hemispherical cartilaginous head that articulates the fin rays (allowing them to move in a circular motion); electric organs present; suboperculum absent; palatine not ossified; maxilla rudimentary.
Siluriformes - catfish
Symplectic, subopercular, basihyal, and intermuscular bones absent; parietals probably present but fused to supraoccipital; mesopterygoid very reduced; preopercle and interopercle relatively small; posttemporal probably fused to supracleithrum but thought by some to be present as a separate element in many families; vomer usually toothed (as is the pterygoid and palatine); dorsal- and anal fin pterygiophores lacking middle radial ossification (as is also true for gymnotiforms), distal radial also absent in silurids; adipose fin usually present; spinelike (=spinous) rays often present at the front of the dorsal and pectoral fins (referred to as spines in family descriptions) (the dorsal fin of most catfishes technically has two spines - the first being very short and forming a locking mechanism for the second spine, which is usually the only one referred to in the family descriptions); body either naked or covered with bony plates; normally up to four pairs of barbels on head, one nasal, one maxillary, and two on chin (i.e., on the lower jaw or mandible), the nasal and chin barbels may be variously absent; maxilla toothless and rudimentary (except in Diplomystidae and the extinct Hypsidoridae), supporting a barbel; principal caudal fin rays 18 or fewer (most with 17); caudal skeleton varying between having six separate hypural plates to complete fusion of caudal elements; eyes usually small (barbels are important in detecting food); air-breathing organs in Clariidae and Heteropneustidae. In contrast to other teleosts, where the urohyal forms as an unpaired ossification of the tendon of the sternohyoideus muscle, which is equivalent to "parurohyal" in siluriforms.
Characiformes - characins
Teeth usually well developed (most are carnivores); adipose fin usually present; body almost always scaled (scales very rarely absent in South American species, e.g., the tetra Gymnocharacinus bergi of Argentina is naked, lacks an adipose fin, and is the most southerly known characiform); probably ctenoid or ctenoidlike scales in some; pelvic fin present (with 5-12 rays); anal fin short to moderately long (fewer than 45 rays); lateral line often decurved, sometimes incomplete; upper jaw usually not truly protractile; pharyngeal teeth usually present, but not usually specialized as in cypriniforms (anostomids have highly modified pharyngeal teeth); barbels absent; branchiostegal rays 3-5; usually 3 postcleithra; first hypural separated from the centrum by a gap in adults (most other primitive teleosts lack such a gap); usually 19 principal caudal fin rays.
Cypriniformes - carps
Kinethmoid present (a median bone between ascending processes of premaxillae); palatine articulating in a socket of the endoptrygoid; fifth ceratobranchial (the pharyngeal bone) enlarged, with teeth ankylosed to the bone (bound by collagenous fibers to the bone in other ostariophysans with teeth, pharyngeal teeth absent in gyrinocheilids); pharyngeal teeth opposed to enlarged posterior process of basioccipital bone (which encloses the dorsal aorta) rather than to upper pharyngeal elements, the basioccipital process against which the pharyngeal teeth press usually covered by a pad (toug horny pad in cyprinids, soft pad in catostomids); ascending process to premaxillae; upper jaw usually protractile; mouth (jaws and palate) always toothless; adipose fin absent (except in some cobitoids); head almost always scaleless; branchiostegal rays three; spinelike rays in dorsal fin of some species. Only two species occur in true marine waters as diadromous species, Tribolodon brandtii (Dybowski, 1872) and Tribolodon sachalinensis (Nikolskii, 1889).
Gonorynchiformes - milkfish
Orbitosphenoid absent; parietals small; quadrate condyle far forward; teeth absent on fifth ceratobranchial; first three vertebrae specialized and associated with one or more cephalic ribs; suprabranchial (=epibranchial) organ present (consisting of lateral pouches in the posterior part of the branchial chamber behind the fourth epibranchials); mouth small; jaws toothless; no postcleithra; 5-7 hypural plates.
Clupeiformes - herrings
Recessus lateralis present (part of the otophysic connection in which various sensory canals merge within a chamber in the otic region of the neurocranium, not known from any other group); parasphenoid teeth absent; no large foramen on the anterior ceratohyal; parietals separated by the supraoccipital; no leptocephalous larvae. Most are plankton feeders, with long and sometimes very numerous gill rakers that serve as straining devices.
Saccopharyngiformes - swallowers and gulpers
Highly aberrant fishes, lacking symplectic bone, opercular bones, branchiostegal rays, scales, pelvic fins, ribs, pyloric caeca, and swim bladder; caudal fin absent or rudimentary; gill openings ventral; dorsal and anal fins long; jaws and hyomandibular greatly elongate, attached to neurocranium by only one condyle; leptocephalous larvae deep-bodied with myomeres V-shaped and not W-shaped. Like anguilliforms, they may spawn once and die.
Anguilliformes - eels and morays
Pelvic fins and skeleton absent; pectoral fins and girdle absent in some; pectoral fins, when present, at least midlateral in position or higher and skeleton lacking bony connection to skull (posttemporal absent); dorsal and anal fins confluent with caudal fin (caudal fin rayless or lost in some); scales usually absent or, if present, cycloid and embedded; body very elongate (eel-like); gill openings usually narrow; gill region elongate and gills displaced posteriorly; gill rakers absent; pyloric caeca absent; maxilla toothed, bordering mouth; the two pre-maxillae (rarely absent), the vomer (usually), and the ethmoid united into a single bone; branchiostegal rays 6-49; swim bladder present, duct usually present; oviducts absent; opisthotic, orbitosphenoid, mesocoracoid, gular plate, posttemporal, postcleithra, supramaxilla, and extrascapular bones absent; ossified symplectic absent (cartilaginous one present in Synaphobranchidae); hyomandibular united with quadrate; ribs present or absent.
Notacanthiformes - halosaurs and deep-sea spiny eels
Body eel-like; posteriorly directed spine on dorsal edge of rear of maxilla; premaxilla and maxilla bordering upper jaw; gill membranes separate; pectoral fins relatively high on body; pelvic fins abdominal, with 7-11 rays (the two fins are usually connected by a membrane); anal fin base long and merged with what remains of the caudal fin; caudal fin skeleton reduced or absent; tail easily regenerated when lost; branchiostegal rays 5-23; swim bladder present. Some have photophores.
Albuliformes - bonefishes
Mandibular sensory canal lying in an open groove in the dentary and angular bones (in all other elopomorphs the groove is roofed, in Albula there is a small roof in the angular).
Elopiformes - tarpons and tenpounders
Pelvic fins abdominal; body slender, usually compressed; gill openings wide; caudal fin deeply forked; caudal fin with seven hypurals; scales cycloid; mesocoracoid and postcleithra present; gular plate well developed (median); branchiostegal rays 23-35; mouth bordered by premaxilla and toothed maxilla; upper jaw extending past eye; tip of snout not overhanging mouth (mouth terminal or superior); no sensory canal extending onto the small premaxilla. Leptocephali small, maximum length about 5 cm, with a well-developed, forked, caudal fin, a posterior dorsal fin (pelvic fins in older larvae), and about 53-86 myomeres.
Osteoglossiformes - bony tongues
Intestine passes posteriorly to left of esophagus and stomach; parasphenoid and tounge bones usually with well-developed teeth and forming a shearing bite (mesopterygoid and usually the ectopterygoid also toothed); premaxilla small and fixed to the skull; no supramaxilla; caudal fin skeleton, except in Hiodon, with large first ural centrum and no urodermals, one or more epurals fused with uroneurals; caudal fin with 16 or fewer branched rays; nasal capsule rigid, no antorbital-supraorbital system for pumping water over olfactory epithelium; epipleural intermuscular bones absent; one or two pyloric caeca, one caecum in Hiodon and Pantodon and two in other osteoglossiforms.
Amiiformes - bowfins
Caudal fin abbreviate heterocercal; dorsal fin base long, with about 48 rays; large median gular plate and 10-13 branchiostegal rays; swim bladder can function as a lung; no pyloric caeca. Maximum length about 90 cm.
Lepisosteiformes - gars
Body and jaws elongate; mouth with needlelike teeth; abbreviated heterocercal tail; heavy ganoid scales, about 50-65 along lateral line; dorsal fin far back, with few rays; three branchiostegal rays; interoperculum absent; two or more supratemporal bones on each side; maxilla small and immobile; supramaxilla absent; myodome absent; vomer paired; swim bladder vascularized (thus permitting aerial respiration); vertebrae opisthocoelous (anterior end convex, posterior end concave, as in some reptiles and unlike all other fish except the blenny Andamia. Maximum length about 3.0 m.
Acipenseriformes - sturgeons and paddlefishes
Caudal fin heterocercal; myodome and preopercle reduced or absent; gulars absent; skeleton largely cartilaginous; fin rays more numerous than their basals; intestine with spiral valve.
Polypteriformes - bichirs
Rhombic ganoid scales; spiracular, opening large but canal lost; dorsal fin consisting of 5-18 finlets, each with a single spine to which is attached one or more soft rays; pectoral fin rays supported by numerous ossified radials which attach to a cartilaginous plate and two rods, thence to the scapula and coracoid; a pair of gular plates, no branchiostegals; maxilla firmly united to skull; intestine with spiral valve; lungs partially used in respiration; vertebrae with ossified centra and neural canal. Maximum length about 90 cm, most species less than 30 cm.