FISHES Pisces Class Osteichthyes -- . Fishes are the best adapted of all the vertebrates to the aquatic realm. Most of our fishes -- in terms of number of species and number of individuals encountered in most streams -- are non-native. With a few exceptions, these freshwater animals are fairly easy to distinguish from one another, especially if captured and placed in an aquarium for observation. A very useful description of fish form and anatomy related to movement and types & terminology of fins (necessary to know in order to use the following key) is provided by Hubbard's Fish Anatomy. Other educational sites with useful diagrams of fish external anatomy include Florida Fish & Game, Badmans Tropical Fish, and Sports Outdoors. [See also CPIE for a list of fresh and brackish water fishes known from Hawai`i]
 Figure 1. Pelvic fin positions |
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| 33a | (26) | Pelvic fins near anus: abdominal in position (Fig. 1, left) | [34] | |
| 33b | Pelvic fins very near, under, or in front of pectoral fins: thoracic in position (Fig. 1, right) | [65] | ||
| 33c |  Without pelvic or pectoral fins; all other fins greatly reduced or not evident. Body eel-like, to 70 cm (24 in) long, tapering at hind end to a point. Taunagi or rice paddy eel. Rare~ Family SYNBRANCHIDAE Monopterus albus (Zuiew)
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| 34a | (33) |
Two widely separated dorsal fins, the first with four spines, second with soft rays. Pectoral fins set high on body. Marine and brackish water, in estuaries and lagoons. Mullets ~ Family MUGILIDAE |
[35] | |
| 34b | Adipose fin (a small, fleshy dorsal lobe without rays, but may be supported by a spine) present behind larger dorsal fin, the latter with or without spines | [36] | ||
| 34c | With a single median, dorsal fin; no separate spiny dorsal in front of a soft dorsal and no adipose fin | [43] | ||
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| 35a | (34 or 72) | Eyes with transparent, adipose lids over front and back edges. Silvery-colored fish with moderately forked tail, usually edged in black. `Ama`ama or striped mullet [ind] Mugil cephalus L.
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| 35b |
Eyes with rudimentary adipose lid not covering eye. Silvery-grey fish with dark pectoral fins (particularly in juveniles). Caudal fin truncate, yellowish to tan in color. Squaretail or yellowtail mullet Liza vaigiensis (Quoy & Gaimard)
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| 35c | Eyes not covered by adipose lids. Caudal fin truncate in juveniles, moderately forked in adults Valamugil engeli (Bleeker)
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| 36a | (34) | Mouth terminal and lacking barbels (fleshy appendages). Scales present | [37] | |
| 36b | Mouth, if terminal or sub-terminal, then having conspicuous barbels; OR mouth ventral (directed downward, under nose) and with or without papillae or barbels. Body with or without scales. Catfishes | [39] | ||
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| 37a | (36) | Fish long, height about 1/5 of total length. Teeth small | [38] | |
| 37b |
Fish length only about three times height. Dark black with flesh-colored to rose under chin and on abdomen. Mouth with very large, conical teeth within. Reservoirs. Pacu ~ Family CHARACIDAE Colossoma macropomum Cuvier
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| 38a | (37) |
Strikingly colored with 5 to 10 black bands on yellowish or orange, bars increasing in number with age. Dorsal fin with 2 spines. Banded leporinus ~ Family CHARACIDAE Leporinus fasciatus (Bloch)
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| 38b |
Body silvery, with black spots and rosy hue along midline. Dorsal fin without spines. Stocked in a few high elevation streams. Rainbow trout ~ Family SALMONIDAE Oncorhyncus mykiss Walbaum
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| 39a | (36) |
Mouth terminal, with long barbels (4 pair) on snout. Body without scales or armor plates, but with serrated pectoral spines. Introduced in some reservoirs. Channel catfish ~ Family ICTALURIDAE Ictaluris punctatus (Rafinesque)
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| 39b | Mouth subterminal or ventral; with or without surrounding papillae or barbels. With scales or armoring | [40] | ||
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| 40a | (39) |
Mouth ventral (directed downward) and surrounded by barbels, but not sucker-like. Body behind head almost triangular in cross-section. Sides armored with two series of overlapping plates; these plates without prickled surfaces. In very few streams. Smooth armored catfish ~ Family CALLICHTHYIDAE Corydoras aeneus (Gill)
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| 39b |
Mouth ventral and sucker-like, with thickened lips. Without barbels, but may have papillae around snout. Body depressed, armored with rough plates, these coated with fine prickles. Very abundant in some urban streams. Spiny armored catfish ~ Family LORICARIIDAE |
[41] | ||
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| 41a | (40) |
Snout margin smooth, fleshy snout tentacles present, at least in adult males. { Largest individuals around 15 cm long. Common in riffle habitat of some O`ahu streams Ancistris cf. temminckii
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| 41b | Snout margin with rough bony plates. { Largest individuals nearly 30 cm long | [42] | ||
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| 42a | (41) |  Dorsal fin rays 7 or 8. Coloration light and dark brown background with dark, circular spots, these smallest on the head, increasing in size posteriorly. Very abundant in pools and riffles of some O`ahu streamHypostomus sp. watwata group
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| 42b | Dorsal fin rays 9 to 14 Pterygoplichthys multiradiatus
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| 43a | (34) | Body narrow-elongate with mouth produced forward as a narrow beak; about 1/4 of total length of fish forward of eye. Dorsal and anal fins about equal in size and shape, located far back from small pelvic fins. Wahiawa Reservoir. Stickfish, needlefish, roundtail garfish ~ Family BELONIDAE Xenentodon cancila (Collette)
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| 43b | Mouth not produced forward as a beak; much less than 1/4 of total length found forward of the eye | [44] | ||
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| 44a | (43) | Body elongate, maximum height less than 1/4 of total length. Mouth terminal or ventral, surrounded by pairs of fleshy appendages (barbels) | [45] | |
| 44b | Body not particularly elongate, or at least maximum height greater than 1/4 total length. Mouth terminal or dorsal or ventral; barbels present or absent | [46] | ||
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| 45a | (44) | Body narrow-elongate (a loach), almost eel-like, to 10-15 cm (4-5 in). Mouth ventral and surrounded by pairs of short barbels. Widespread in freshwater streams. Dojo or weatherfish ~ Family COBITIDAE Misgurnus anguillicaudatus (Cantor)
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| 45b |  Body not loach-like, but elongate, Mouth ventral and surrounded by
four pairs of long barbels. Widespread in freshwater streams, but
secretive; in deeper pools. Puntat or Chinese catfish~ Family CLARIIDAE Clarius fuscus
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| 46a | (44) | Lower jaw protruding and square viewed from above; mouth directed upwards and without barbels. Anal fin of males modified as an intromittent organ (long and narrow) located close to pelvic fins. Topminnows or toothed carps ~ Family POECILIIDAE |
[47] | |
| 46b | Lower jaw not protruding: mouth either terminal or ventral (directed downwards). Anal fin normal in both sexes and distant from pelvic fins. Carps and minnows ~ Family CYPRINIDAE |
[55] |