Dichotomous key for identification of the fishes of Texas found in freshwaters

The key provided here is a verbatim version of the key found in:

Hubbs, C., R. J. Edwards and G. P. Garrett. 2008. An annotated checklist of the freshwater fishes of Texas, with keys to identification of species (Third Edition). Texas Academy of Science special electronic publication available from: http://www.texasacademyofscience.org/. or from the Hubbs Ichthyological Society.

We have adapted that key here to be interactive, in hopes that might make it more user friendly. Further development of this version of the key is now part of the Fishes of Texas Project. We hope to regularly update it as changes are made, and to add fish images, as well as images of the anatomical features used in the key, along with direct links to species accounts and other helpful information.

We also hope to invoke the community of users of this key in helping to improve it. Please email comments to Dr. Dean Hendrickson (deanhend_at_mail.utexas.edu).

You can jump to the family if you already know it using these shortcuts:

Achiridae, Acipenseridae, Amiidae, Anguillidae, Aphredoderidae, Ariidae, Atherinopsidae, Belonidae, Carangidae, Carcharhinidae, Catostomidae, Centrarchidae, Centropomidae, Characidae, Cichlidae, Clupeidae, Cyprinidae, Cyprinodontidae, Dasyatidae, Doradidae, Elassomatidae, Eleotridae, Elopidae, Engraulidae, Esocidae, Fundulidae, Gerreidae, Gobiidae, Haemulidae, Hiodontidae, Ictaluridae, Lepisosteidae, Loricariidae, Megalopidae, Moronidae, Mugilidae, Ophichthidae, Paralichthyidae, Percidae, Petromyzontidae, Poeciliidae, Polynemidae, Polyodontidae, Pristidae, Salmonidae, Sciaenidae, Sparidae, Syngnathidae, Tetraodontidae

or start with our

Key to Families

1a Pelvic fins absent - 2

1b Pelvic fins present - 6

2a Jaws absent; pectoral fins absent; 7 pairs of gill openings - PETROMYZONTIDAE

2b Jaws present; pectoral fins small; 1 pair of gill openings - 3

3a Dorsal fin attached to caudal fin; dorsal fin base goes less than 2 times in body length; upper jaw extends beyond eye - 4

3b Dorsal fin free from caudal fin base; dorsal fin base goes more than 4 time in body length; upper jaw does not reach vertical from eye - 5

4a Posterior nostril just above lower lip; scales absent; upper jaw projects further than lower jaw - OPHICHTHIDAE

4b Posterior nostril well above level of lower lip, even with a horizontal line through lower margin of eye; scales present (they are small and embedded); lower jaw projects further than upper jaw - ANGUILLIDAE

5a Body with plates; snout long and tubular - SYNGNATHIDAE

5b Body without plates; snout blunt - TETRAODONTIDAE

6a Five pairs of gill slits - 7

6b One pair of gill slits - 9

7a Gill slits dorsal to pectoral fins; body rounded - CARCHARHINIDAE

7b Gill slits ventral to pectoral fins; body depressed - 8

8a Snout elongate with sharp, saw-like teeth; no spines on dorsal surface - PRISTIDAE

8b Snout short and blunt; sharp spine on dorsal surface of tail; body very much flattened - DASYATIDAE

9a Caudal fin heterocercal - 10

9b Caudal fin homocercal - 13

10a Caudal fin strongly heterocercal; mouth inferior - 11

10b Caudal fin abbreviated heterocercal; mouth terminal - 12

11a Body not armored; snout paddle-like with 2 small barbels - POLYODONTIDAE

11b Body with several bony scutes; snout not more than ⅔ of head length; 4 elongate barbels - ACIPENSERIDAE

12a Scales ganoid; snout produced into an elongate beak; dorsal fin short, its origin posterior to the origin of the anal fin - LEPISOSTEIDAE

12b Scales cycloid; snout blunt; dorsal fin long, its origin anterior to the origin of the pelvic fin - AMIIDAE

13a Both eyes on same side of head; dorsal and anal fins both with more than 25 soft fin rays - 14

13b Eyes on each side of head or absent; either dorsal or anal fin (or both) with fewer than 25 soft fin rays - 15

14a Edges of preopercle hidden by skin; no left pectoral fin - ACHIRIDAE

14b Edges of preopercle not hidden by skin; both pectoral fins present - PARALICHTHYIDAE

15a Pelvic fins without a spine, and with more than 5 soft fin rays; anal fin with no spines; 1 dorsal fin with fin rays - 16

15b Pelvic and anal fins with 1 or more spines; 1 or more dorsal fins with fin rays - 33

16a Adipose fin present - 17

16b No adipose fin - 22

17a Body scaled; head without barbels - 18

17b Body not scaled; head with 4 to 8 barbels if naked, otherwise body with bony plates - 19

18a Fewer than 50 lateral line scales - CHARACIDAE

18b More than 60 lateral line scales - SALMONIDAE

19a Body covered with bony plates - 20

19b Body naked; head with 4 to 8 barbels - 21

20a Three pairs of barbels; lateral row of armored scutes with spike-like extensions along the center of the plates; adipose fin - DORADIDAE

20b No barbels; no spiked scutes; adipose fin with anterior spine - LORICARIIDAE

21a Nostrils close together, posterior nostril without a barbel - ARIIDAE

21b Nostrils far apart, posterior nostril with a barbel - ICTALURIDAE

22a Head scaleless - 23

22b Head partly scaled - 29

23a Branchiostegal membranes free from isthmus; gill slits extend far forward below jaws - 24

23b Branchiostegal membranes united to isthmus, gill slits do not extend far forward below jaws; no teeth on jaws - 28

24a Mouth subinferior, below a tapering pig-like snout; upper jaw long, reaching beyond posterior margin of preopercle - ENGRAULIDAE

24b Mouth variable, but if inferior, upper jaw not reaching behind eye - 25

25a Lateral line absent; scales along midline of belly modified to form a saw-like keel - CLUPEIDAE

25b Lateral line present; scales along midline of belly undifferentiated - 26

26a Upper jaw not extending posterior to eye; dorsal fin above anal fin; gular plate absent - HIODONTIDAE

26b Upper jaw extending posterior to eye; dorsal fin above pelvic fin; gular plate present - 27

27a Mouth terminal; last dorsal fin ray not elongated - ELOPIDAE

27b Mouth superior; last dorsal fin ray elongated - MEGALOPIDAE

28a Pharyngeal teeth numerous (>9) and comb-like; distance from anal fin origin to caudal fin base less than ½ the distance from the dorsal fin origin to caudal fin base; mouth adapted for sucking - CATOSTOMIDAE

28b Fewer than 9 pharyngeal teeth on each side; distance from anal fin origin to caudal fin base more than ½ the distance from the dorsal fin origin to caudal fin base; mouth not adapted for sucking - CYPRINIDAE

29a Snout needle-shaped; lateral line very low - BELONIDAE

29b Snout not needle-shaped; lateral line, if present, median in position - 30

30a Snout duck-billed or paddle shaped; caudal fin forked; lateral line median in position - ESOCIDAE

30b Snout blunt; caudal fin rounded, incomplete lateral line - 31

31a Origin of dorsal fin above or anterior to origin of anal fin; oviparous; adult males with a rounded anal fin; 3rd soft ray in anal fin branched in both sexes - 32

31b Origin of dorsal fin posterior to origin of anal fin; viviparous; adult males with a modified anal fin forming a gonopodium; 3rd soft ray in anal fin un-branched in both sexes - POECILIIDAE

32a Teeth conical and simple; 8 to 13 scale rows from pelvic origin to isthmus - FUNDULIDAE

32b Teeth compressed and with 3 cusps; belly naked or with more than 15 scale rows from pelvic origin to isthmus - CYPRINODONTIDAE

33a Anus anterior to pelvic fins; pelvic fins with more than 5 soft fin rays - APHREDODERIDAE

33b Anus posterior to pelvic fins; pelvic fins with 5 soft fin rays - 34

34a Pelvic fins abdominal or subthoracic; dorsal fins well separated - 35

34b Pelvic fins thoracic (insertion underneath front third of pectoral fin rays); dorsal fins separate or united - 37

35a Pectoral fin with 5 to 8 lower fin rays detached and filamentous - POLYNEMIDAE

35b Pectoral fin entire - 36

36a Three anal fin spines; 4 stout dorsal fin spines - MUGILIDAE

36b One anal fin spine; 4 to 8 slender dorsal fin spines - ATHERINOPSIDAE

37a Posterior part of lateral line with well developed spiny scutes; the 2 anal fin spines separated - CARANGIDAE

37b Posterior part of lateral line (if present) unarmored; 1 to 8 anal fin spines, connected by membranes - 38

38a Nostrils single on each side; lateral line interrupted - CICHLIDAE

38b Nostrils double on each side; lateral line complete, incomplete or absent - 39

39a Lateral line extending onto tip of middle fin rays of caudal fin - 40

39b Lateral line, if present, not extending beyond base of caudal fin - 42

40a One or 2 anal fin spines; mouth inferior; dorsal fin single; caudal rounded - SCIAENIDAE

40b Three anal fin spines - 41

41a Two separate dorsal fins - CENTROPOMIDAE

41b Dorsal fins continuous - HAEMULIDAE

42a Gill membranes broadly joined to isthmus; lateral line absent - 43

42b Gill membranes free or nearly free from isthmus (may be joined to each other across isthmus); lateral line present or absent - 44

43a Pelvic fins separate - ELEOTRIDAE

43b Pelvic fins joined into a sucking disk - GOBIIDAE

44a Premaxillaries excessively protractile, their basal processes very long; a groove at the top of the cranium - GERREIDAE

44b Premaxillaries moderately protractile or not protractile; no groove at the top of the cranium - 45

45a Jaw teeth prominent incisors; molar teeth on roof and floor of mouth - SPARIDAE

45b All teeth canines - 46

46a One or 2 anal fin spines, the 1st usually distinctly longer than the 2nd (if present) - PERCIDAE

46b Three or more anal fin spines, the 3rd distinctly longer than the 1st - 47

47a Opercle with a spine; pseudobranchium well developed and uncovered - MORONIDAE

47b Opercle without a spine; pseudobranchium absent or covered with skin - 48

48a Four or 5 dorsal fin spines; lateral line absent; scales cycloid; 5 branchiostegals - ELASSOMATIDAE

48b Six to 13 dorsal fin spines; lateral line present; scales ctenoid; 6 or 7 branchiostegals - CENTRARCHIDAE

 

KEY TO ACHIRIDAE

1a Right pectoral fin absent; 66 to 75 lateral line scales - Trinectes maculatus

1b Right pectoral fin present; 75 to 85 lateral line scales - Achirus lineatus

KEY TO ACIPENSERIDAE

- Scaphirhynchus platorynchus

KEY TO AMIIDAE

- Amia calva

KEY TO ANGUILLIDAE

- Anguilla rostrata

KEY TO APHREDODERIDAE

- Aphredoderus sayanus

KEY TO ARIIDAE

1a Lower jaw with 4 barbels; pectoral and dorsal fins with long filaments - Bagre marinus

1b Lower jaw with 6 barbels; pectoral and dorsal fins without long filaments - Ariopsis felis

KEY TO ATHERINOPSIDAE

1a Jaws produced into a short beak; snout length much longer than eye length; scales small, more than 60 scales in lateral series; more than 20 anal fin rays - Labidesthes sicculus

1b Jaws not produced into a beak; snout length equal to or shorter than eye length; scales large, usually fewer than 50 in lateral series; fewer than 20 anal fin rays - 2

2a Scales ctenoid, rough to the touch; double pairs of dark spots on dorsum; bases of dorsal and anal fin covered with scales - Membras martinica

2b Scales cycloid, smooth to the touch; dorsum with crosshatching, but not double pairs of dark spots; bases of dorsal and anal fins not covered with scales - 3

3a Usually 8 second dorsal fin rays; air bladder long and opaque when viewed in bright light, with usually 4 or more anal fin rays in front of the posterior tip of the air bladder; only exists as females - Menidia clarkhubbsi

3b Usually 9 second dorsal fin rays; air bladder long and transparent or short and opaque; either male or female - 4

4a Air bladder long and transparent, its posterior tip smoothly rounded; usually 4 or more anal fin rays in front of the posterior tip of the air bladder; horizontal distance between spinous dorsal and anal fin origin less than 7% of standard length - Menidia beryllina

4b Air bladder short and opaque, its posterior tip blunt and rectangular; usually 3 or fewer anal fin rays in front of the posterior tip of the air bladder; horizontal distance between spinous dorsal and anal fin origin greater than 7% of standard length - Menidia peninsulae

KEY TO BELONIDAE

- Strongylura marina

KEY TO CARANGIDAE

- Caranx hippos

KEY TO CARCHARHINIDAE

1a Teeth smooth; length of longest gill slit more than ⅓ of the height of the dorsal fin; head triangular in front of nostrils - Carcharhinus isodon

1b Teeth serrate; length of longest gill slit less than ¼ of the height of the dorsal fin; head bluntly rounded in front of nostrils - Carcharhinus leucas

KEY TO CATOSTOMIDAE

1a Dorsal fin base more than ⅓ of standard length; 22 to 30 dorsal fin rays - 2

1b Dorsal fin base less than ¼ of standard length; 4 to 18 dorsal fin rays - 7

2a More than 50 lateral line scales; eye closer to back of head than to tip of snout; head abruptly more slender than body (in adults) - 3

2b Fewer than 45 lateral line scales; eye closer to tip of snout than back of head; head gradually more slender than body - 4

3a Lip papillae short, only around mouth - Cycleptus elongatus

3b Lip papillae long, extending forwards onto end of snout - Cycleptus sp.

4a Subopercle broadest below middle, subtriangular; cheek deep and long (eye about equidistant between the upper corner of the gill slit and the posteroventral angle of the preopercle) - Carpiodes carpio

4b Subopercle broadest at middle, subsemicircular; cheek shallow and foreshortened (distance from eye to posteroventral angle of preopercle ¾ of distance to upper corner of the gill slit - 5

5a Mouth large and very oblique; upper jaw as long as snout; upper lip about level with the lower margin of orbit; lips thin and faintly striate - Ictiobus cyprinellus

5b Mouth small and a little oblique; upper jaw distinctly shorter than snout; upper lip well below the lower margin of orbit; lips thick and coarsely striate - 6

6a Body more elongate, greatest depth goes 2.6 to 3.3 times in standard length; thickness of head goes fewer than 5 times in standard length; distance from the posterior tip of the maxillary to the front of mandible greater than eye length (about twice eye length in large adults) - Ictiobus niger

6b Body deeper and narrower, greatest depth goes 2.2 to 2.8 times in standard length; thickness of head goes more than 5 times in standard length; distance from the posterior tip of the maxillary to the front of the mandible less than eye length (about equal to eye in large adults) - Ictiobus bubalus

7a Lateral line complete and well developed in adults; air bladder with 3 chambers - 8

7b Lateral line incomplete or absent in adults; air bladder with 2 chambers - 11

8a Caudal fin with a black streak on lower lobe - Moxostoma poecilurum

8b Caudal fin without a black streak - 9

9a Dorsal fin rays 13; tip of dorsal fin blackish; caudal fin yellowish; lower sides golden to red - Moxostoma erythrurum

9b Dorsal fin rays 11 or 12; distal half of dorsal fin membranes dusky; caudal fin dusky; lower sides olive to yellow - 10

10a Pectoral fin length equal to head length; width of eye goes 4 to 5.5 times into head length; 44 to 46 scales along the lateral line - Moxostoma congestum

10b Pectoral fin length less than head length; width of eye goes nearly 5.5 times into head length; 47 to 50 scales along the lateral line - Moxostoma austrinum

11a Lateral line somewhat developed in adults; mouth inferior and horizontal; color pattern (except in the pale, obscurely mottled young) consists of rows of black spots (1 on each scale) - Minytrema melanops

11b Lateral line always absent; mouth subterminal and oblique; color pattern (except in young with 2 dark stripes) consists of narrow vertical bars - 12

12a Longitudinal scale rows 34 to 38 (usually 36 to 38); eye larger (eye length approximately ½ of snout length), back with crescentric scale marks - Erimyzon sucetta

12b Longitudinal scale rows 39 to 43 (usually 39 to 41); eye smaller (eye length goes more than 2 times in snout length), back without crescentric scale marks - Erimyzon oblongus

KEY TO CENTRARCHIDAE

1a Anal spines 3 (rarely 2 or 4) - 2

1b Anal spines 5 to 8 - 15

2a Body depth usually goes 3 to 5 times in standard length; more than 55 lateral line scales - 3

2b Body depth usually goes 2 to 2.5 times in standard length; fewer than 55 lateral line scales - 6

3a Shortest dorsal fin spine goes 2.4 to 3.9 times in longest dorsal spine; bases of soft dorsal and anal fins without scales; pyloric caecae branched at base - Micropterus salmoides

3b Shortest dorsal fin spine goes 1.1 to 2.5 times in longest dorsal spine; bases of soft dorsal and anal fins scaled; pyloric caecae not branched - 4

4a Dorsal fin soft rays 12; 28 to 32 scales around caudal peduncle; 11 to 14 scales above lateral line; 19 to 25 scales below lateral line - Micropterus dolomieu

4b Dorsal fin soft rays 13 to 15; 22 to 28 scales around caudal peduncle; 7 to 10 scales above lateral line; 14 to 19 scales below lateral line - 5

5a Small spots on scales not present dorsal to lateral line; dark lateral stripe prominent; caudal spot prominent; maximum depth of bars making up lateral stripe goes 3 to 4 times into maximum body depth - Micropterus punctulatus

5b Small spots on scales extend to near dorsal; dark lateral stripe obscured by barring; caudal spot usually indistinct (more so in adults); maximum depth of bars on body goes 1.5 to 2 times into maximum body depth - Micropterus treculii

6a Teeth on tongue and pterygoids; supramaxilla longer than breadth of maxilla; maxillary width exceeds suborbital - Lepomis gulosus

6b No teeth on tongue or pterygoids; supramaxilla absent or shorter than breadth of maxilla; maxillary width less than suborbital - 7

7a Pectoral fins short and rounded going 3.75 or more times in standard length - 8

7b Pectoral fins long and pointed, upper pectoral fin rays much longer than lower; pectoral fin goes 3.5 or fewer times in standard length - 13

8a Opercle stiff to its margin (not including membrane); posterior edge of opercle within opercular membrane smooth - 9

8b Opercle produced into a thin flexible projection lying within the opercular membrane; posterior edge of opercle within opercular membrane fimbriate - 11

9a Fewer than 40 scales on incomplete lateral line; black spot on dorsal fin with a light margin in young - Lepomis symmetricus

9b More than 35 scales on complete lateral line; black spot, if present on dorsal fin, without a light margin - 10

10a Dark spot at posterior base of dorsal fin; gill rakers in adults long, when depressed reaching beyond base of 2nd raker below; supramaxilla ⅔ width of maxilla - Lepomis cyanellus

10b No dark spot at posterior base of dorsal fin; gill rakers in adults short, when depressed not reaching base of 2nd raker below; supramaxilla ⅓ width of maxilla - Lepomis miniatus

11a Palatine teeth present; opercular membrane dark to its margin - Lepomis auritus

11b Palatine teeth absent; opercular membrane not dark to its margin - 12

12a Cheek scales 3 to 5; 12 (rarely 13) pectoral fin rays; 33 to 40 lateral line scales; anal base convex - Lepomis marginatus

12b Cheek scales 5 to 7; 13 to 15 pectoral fin rays; 38 to 49 lateral line scales; anal base nearly straight - Lepomis megalotis

13a Opercle margined with scarlet (normally faded in preserved material), stiff to its margin; gill rakers short, not reaching beyond base of 2nd raker below when depressed - Lepomis microlophus

13b Opercle not margined with scarlet, flexible; gill rakers reaching at least to base of 2nd below when depressed - 14

14a Anal fins with 7 to 9 soft rays; no dark spot on posterior part of dorsal fin; palatine teeth present - Lepomis humilis

14b Anal fins 10 to 12 soft rays; a dark spot on posterior part of dorsal fin; palatine teeth absent - Lepomis macrochirus

15a Dorsal fin spines 11 to 13 - 16

15b Dorsal fin spines 6 to 8 - 17

16a Anal fin with 6 spines and 10 to 11 soft rays; fewer than 20 gill rakers on 1st arch; preopercle entire or weakly crenate - Ambloplites rupestris

16b Anal fin with 7 to 8 spines and 13 to 15 soft rays; more than 24 gill rakers on 1st arch; preopercle finely serrate - Centrarchus macropterus

17a Dorsal fin spines (usually) 6; length of dorsal fin base less than distance from its origin to posterior margin of eye; body pigmentation in vertical bands - Pomoxis annularis

17b Dorsal fin spines 7 or 8; length of dorsal fin base equal to or greater than distance from its origin to posterior margin of eye; body pigmentation in scattered spots - Pomoxis nigromaculatus

KEY TO CENTROPOMIDAE

1a Second anal fin spine not reaching to caudal fin base; tips of pelvic fins reaching barely to anus; 9 to 10 gill rakers on lower arch - Centropomus undecimalis

1b Second anal fin spine reaching past caudal fin base; tips of pelvic fins reaching past anus; 13 to 16 gill rakers (excluding rudiments) on lower arch - Centropomus parallelus

KEY TO CHARACIDAE

- Astyanax mexicanus

KEY TO CICHLIDAE

1a Anal fin spines 5 or 6 - Cichlasoma cyanoguttatum

1b Anal fin spines fewer than 5 (usually 3) - 2

2a Gill rakers 8 to 10 on lower part of 1st gill arch; transverse bands present on sides; dorsal fin with yellow spots - Tilapia zillii

2b Gill rakers 14 or more on lower part of 1st gill arch; color pattern other than that above - 3

3a Gill rakers 14 to 20 (usually 17 to 18) on lower part of first gill arch; most teeth in outer row are unicuspid in adults; sides with 3 or 4 dark blotches or with no markings; no yellow on dorsal fin; caudal fin without distinct vertical stripes - Oreochromis mossambicus

3b Gill rakers 18 to 26 on lower part of 1st gill arch; outer row of teeth bicuspid in adults; caudal fin unmarked, or with vague, irregular dark markings, caudal fin often with a broad, red distal margin; young often with vertical bands on caudal fin - Oreochromis aureus

KEY TO CLUPEIDAE

1a Last ray of dorsal fin not elongated; mouth terminal or superior - 2

1b Last ray of dorsal fin greatly elongated; lower jaw included - 4

2a Posterior margins of lateral scales fluted or pectinated; more than 60 longitudinal scale rows - Brevoortia gunteri

2b Posterior margins of lateral scales entire; fewer than 60 longitudinal scale rows - 3

3a Body depth goes fewer than 3 times in standard length; more than 30 gill rakers below angle of 1st arch - Harengula jaguana

3b Body depth goes more than 3 times in standard length; fewer than 30 gill rakers below angle of 1st arch - Alosa chrysochloris

4a Twenty nine to 33 anal fin rays; base of dorsal fin contained 1.0 to 1.6 times in last ray length; black shoulder spot (especially in young) equal to or larger than pupil; mouth below level of middle of eye - Dorosoma cepedianum

4b Twenty four to 28 anal fin rays; base of dorsal fin contained 1.5 to 1.8 times in last ray length; black shoulder spot (especially in young) smaller than pupil; mouth at level of eye - Dorosoma petenense

KEY TO CYPRINIDAE

1a More than 15 soft rays on dorsal fin; dorsal and anal fins each with a strong serrated spine - 2

1b Fewer than 10 soft rays on dorsal fin; dorsal and anal fins without spines - 3

2a Upper jaw with 2 long, fleshy barbels on each side; 35 to 38 lateral line scales (except mirror and leather carps); pharyngeal teeth 1,1,3-3,1,1 - Cyprinus carpio

2b Upper jaw without barbels; 26 to 29 lateral line scales; pharyngeal teeth 4-4 - Carassius auratus

3a Pharyngeal teeth with prominent parallel grooves; distance from anal fin origin to end of caudal peduncle goes 3 or more times in distance from tip of snout to anal fin origin - Ctenopharyngodon idella

3b Pharyngeal teeth without prominent parallel grooves; distance from anal fin origin to end of caudal peduncle goes 2.5 or fewer times in distance from tip of snout to anal fin origin - 4

4a Cartilaginous ridge of lower jaw prominent and separated by a definite groove from lower lip; intestine wound spirally around the air bladder - 5

4b Cartilaginous ridge of lower jaw hardly evident and not separated by a definite groove from the lower lip; intestine not wound spirally around the air bladder - 6

5a Lower jaw length greater than eye length; more than 65 lateral line scales - Campostoma ornatum

5b Lower jaw length less than eye length; fewer than 60 lateral line scales - Campostoma anomalum

6a Premaxillaries not protractile; upper lip connected with skin of snout by a frenum - Rhinichthys cataractae

6b Premaxillaries protractile; upper lip separated from skin of snout by a deep groove continuous across the midline - 7

7a Lateral line greatly decurved - 8

7b Lateral line usually not decurved, either straight or with a broad arch - 9

8a Abdomen behind pelvic fins with a fleshy keel over which the scales do not pass; pharyngeal teeth in 1 row (4-4 or 5-5); gill rakers long and slender, 17 to 19 on the 1st gill arch; eyes and median fins usually yellow-green - Notemigonus crysoleucas

8b Abdomen behind pelvic fins scaled; pharyngeal teeth in 2 rows (3,5-5,3 or 2,5-5,2); gill rakers short and stout, 9 to 10 on the first gill arch; eyes and fins usually red - Scardinius erythrophthalmus

9a Pharyngeal teeth in main row typically 5-5 or 4-4 - 10

9b Pharyngeal teeth in main row typically 4-4 - 11

10a Mouth very small, almost vertical; no pharyngeal teeth in lesser row - Opsopoeodus emiliae

10b Mouth large and only moderately oblique; 2 pharyngeal teeth in lesser row - Semotilus atromaculatus

11a Maxillary barbels present - 12

11b No maxillary barbels - 18

12a Body speckled (for most specimens >20 mm standard length); pharyngeal teeth 4-4 - 13

12b Body always silvery; pharyngeal teeth in 2 rows - 17

13a Two pairs of barbels; posterior barbels longer than orbit length; anterior barbels usually half of orbit length; lips fleshy and thickened posteriorly; breeding males with 3 or 4 rows of tubercles on pectoral fin membranes - 14

13b One or 2 pairs of barbels; posterior barbels less than orbit length, anterior barbels, if present, less than half anterior barbel length; lips not fleshy; breeding males with 1 or 2 rows of tubercles on pectoral fin membranes - 15

14a Anal fin rays usually 7; pectoral fins in adult males falcate, reaching beyond base of pelvic fin - Macrhybopsis australis

14b Anal fin rays usually 8; pectoral fins of adult males rounded, barely reaching pelvic fin base - Macrhybopsis tetranema

15a Lateral stripe absent or most distinct on posterior portion of body - 16

15b Lateral stripe distinct along side of body - Macrhybopsis marconis

16a Lateral stripe absent; 20 to 50 scales above lateral line with clusters of melanophores - Macrhybopsis aestivalis

16b Lateral stripe present; few scales above lateral line with clusters of melanophores - Macrhybopsis hyostoma

17a Pharyngeal teeth 2,4-4,2; lateral line scales 49 to 57; occiput depth less than width; small barbel present at corner of mouth - Platygobio gracilis

17b Pharyngeal teeth 1,4-4,1; fewer than 50 lateral line scales; depth at occiput greater than width - Macrhybopsis storeriana

18a Lower lip thick with a fleshy lobe on each side that is partially separated from the mandible by a groove (best observed from the front) - Phenacobius mirabilis

18b Lower lip thin, without a fleshy lobe - 19

19a More than 50 lateral line scales - Gila pandora

19b Fewer than 45 lateral line scales - 20

20a Predorsal scales crowded; much smaller than those on rest of body; 7 anal fin rays; first 2 obvious dorsal fin rays stout, well separated from the following well developed but unbranched ray by a membrane - 21

20b Predorsal scales not crowded except for fish with 9 or more anal fin rays; first obvious dorsal fin ray a thin splint, closely attached to the following well developed but unbranched ray, especially at tip - 22

21a Intestine long, more than twice standard length; caudal spot not separated from the longitudinal streak by a clear space - Pimephales promelas

21b Intestine short, forming a simple S-shaped loop; caudal spot separated from the longitudinal streak by a clear area - Pimephales vigilax

22a Intestinal canal long, more than twice standard length - 23

22b Intestinal canal short, forming a simple S-shaped loop - 31

23a A black band through eye to snout; eye as long as snout - 24

23b No black band through eye to snout; eye shorter than snout - 28

24a Seven anal fin rays - Dionda serena

24b Eight anal fin rays - 25

25a Caudal peduncle depth wide; long postorbital - 26

25b Caudal peduncle depth narrow; short postorbital - 27

26a Typically 38 or more lateral line scales - Dionda episcopa

26b Typically 37 or fewer lateral line scales - Dionda nigrotaeniata

27a Double dashes present along lateral line canal; caudal spot wedge-shaped; prominent markings on dorsal scale pockets - Dionda diaboli

27b Lateral line canal without double dashes; caudal spot rounded; no prominent markings on dorsal scale pockets - Dionda argentosa

28a Mid-dorsal with a thin stripe flanked on each side by another faint dark stripe - Hybognathus hayi

28b Mid-dorsal stripe broad and solid - 29

29a Head width about equal to distance from tip of snout to back of eye; 11 to 15 scale rows across belly (counted just in advance of pelvic insertion, excluding the lateral line scales); eye contained in snout about 1.5 times - 30

29b Head width considerably greater than distance from tip of snout to back of eye; 14 to 22 scale rows across belly; eye contained in snout about 2 times - Hybognathus placitus

30a Scales with 10 radii - Hybognathus nuchalis

30b Scales with 8 radii - Hybognathus amarus

31a Mouth terminal and oblique; pharyngeal teeth in 2 rows, 1 or 2,4-4,2 or 1 (except in Cyprinella lutrensis) - 32

31b Mouth subinferior and horizontal; pharyngeal teeth 4-4 (except in Hybopsis amnis and Notropis braytoni) - 60

32a Dorsal fin less triangular, the last fin ray about ½ the length of the longest; interradial membranes of dorsal fin with melanophores (weak or lacking in young and female Cyprinella proserpina) - 33

32b Dorsal fin more triangular, the last fin ray less than ½ the length of the longest; interradial membranes of dorsal fin without melanophores (except along rays and except in Pteronotropis hubbsi which has more than 8 anal fin rays and a prominent lateral stripe ending in a caudal spot) - 36

33a Caudal fin base with a large black spot (larger than eye); no dark bar above pectoral fin base - Cyprinella venusta

33b Caudal fin base without a large black spot; a dark bar above pectoral fin base - 34

34a Tubercles on head of high males larger on snout than on occiput; a distinct black median stripe from the chin to the isthmus; snout length greater than upper jaw length - Cyprinella proserpina

34b Tubercles on head of dominant males larger on occiput than on snout; the black median stripe on chin extends no farther posteriorly than below eye; upper jaw length greater than snout length - 35

35a Mouth slightly subinferior; head blunt and rounded; snout length plus upper jaw length 17% or less of standard length; body more slender, distance between dorsal and anal fin origins 24 to 29% of standard length (higher figures for adult males, lower figures for females and young) - Cyprinella lepida

35b Mouth more terminal; head sharp and compressed; snout length plus upper jaw length 17% or more of standard length; body usually deeper, distance between dorsal and anal fin origins 26 to 36% of standard length (higher figures for adult males, lower figures for females and young) - Cyprinella lutrensis

36a Usually 9 to 12 anal fin rays; pharyngeal teeth typically 2,4-4,2 - 37

36b Usually 6 to 8 anal fin rays; pharyngeal teeth typically 1,4-4,1 - 47

37a Origin of dorsal fin opposite insertion of pelvic fin; dorsal origin nearer tip of snout than base of caudal fin - 38

37b Origin of dorsal fin behind insertion of pelvic fin; dorsal origin nearer base of caudal fin than tip of snout - 41

38a Scales with dark markings forming longitudinal stripes; exposed portions of lateral line scales greatly elevated; more than 18 predorsal scales - Luxilus chrysocephalus

38b Sides of body silvery; exposed portions of lateral line scales not markedly elevated; fewer than 17 predorsal scales - 39

39a Usually 8 anal fin rays; depth at occiput more than width at occiput - Notropis shumardi

39b Usually 7 anal fin rays; depth at occiput less than width at occiput - 40

40a Mid-dorsal stripe about 5 chromatophores wide; iris black; about 15 chromatophores on line between orbits; snout definitely overhanging mouth - Notropis potteri

40b Mid-dorsal stripe about 10 chromatophores wide; iris with some white anteriorly and posteriorly; more than 30 chromatophores on line between orbits; snout not definitely overhanging mouth - Notropis blennius

41a Scales small, 41 or more in lateral line; 25 or more predorsal scales - 42

41b Scales large, 40 or fewer in lateral line; 24 or fewer predorsal scales - 43

42a Dorsal fin with prominent black spot at base of anterior rays; origin of dorsal fin midway between base of caudal fin and front of eye or nostril - Lythrurus umbratilis

42b Dorsal fin without prominent black spot; origin of dorsal fin midway between base of caudal fin and pupil - Lythrurus fumeus

43a Prominent black lateral stripe extending through eye and ending in a caudal spot ½ of caudal peduncle depth - Pteronotropis hubbsi

43b No caudal spot; either fewer than 10 anal fin rays or no prominent black lateral stripe - 44

44a No chromatophores on lateral line scales other than on lateral stripe; mid-dorsal stripe behind dorsal fin usually 1 to 2 chromatophores wide - 45

44b A few chromatophores on lateral line scales other than those on lateral stripe; mid-dorsal stripe behind dorsal fin usually 3 to 5 chromatophores wide - 46

45a Eye larger, contained about 2.5 to 3 times in body depth (measured over curve); black lips - Notropis amabilis

45b Eye smaller, contained about 4 times in body depth (measured over curve); no black lips (may be dusky) - Notropis jemezanus

46a Eye shorter than snout; underside of opercle light - Notropis oxyrhynchus

46b Eye longer than snout; underside of opercle gray - Notropis atherinoides

47a Eye large, contained about 2.5 to 3 times in body depth (measured over curve) - Notropis amabilis

47b Eye small, contained about 3.5 to 4 times in body depth (measured over curve) - 48

48a No paired dots along lateral line - 49

48b Paired dots along lateral line - 57

49a Prominent black lateral stripe extending through eye and ending in a caudal spot; lateral line incomplete - Notropis maculatus

49b No prominent lateral stripe extending through eye; no caudal spot; lateral line complete - 50

50a Depth at occiput more than width at occiput; usually 8 anal fin rays - 51

50b Depth at occiput equal to or less than width at occiput; usually 7 anal fin rays - 54

51a Dorsal fin insertion well behind insertion of pelvic fin, nearer base of caudal fin than tip of snout - 52

51b Dorsal fin insertion opposite insertion of pelvic fin, nearer tip of snout than base of caudal fin - 53

52a Usually 8 anal fin rays; 9 or 10 gill rakers on 1st gill arch; 14 to 16 rakers on 2nd arch; 10 or 11 rakers on 3rd arch; pharyngeal arch slender; posterior edge of jaw does not reach pupil - Notropis orca

52b Usually 9 or 10 anal fin rays; 6 to 8 gill rakers on 1st gill arch; 11 to 13 rakers on 2nd arch; 8 or 9 rakers on 3rd arch; pharyngeal arch broad; posterior edge of jaw under pupil - Notropis simus

53a Pectoral fin length goes more than 5 times in standard length; no caudal spot - Notropis shumardi

53b Pectoral fin length goes fewer than 4 times in standard length; caudal spot faint - Notropis braytoni

54a Dorsal stripe conspicuously interrupted in base of dorsal fin, producing a dark dash at base of dorsal fin - 55

54b Dorsal stripe not conspicuously interrupted in base of dorsal fin - 56

55a Snout length greater than distance from anterior tip of mandible to posterior tip of maxillary; head depth 15.9 to 17.7% of standard length; opercle length 8.0 to 9.6% of standard length - Notropis buccula

55b Snout length shorter than distance from anterior tip of mandible to posterior tip of maxillary; head depth 17.4 to 19.5% of standard length; opercle length 9.5 to 11.4% of standard length - Notropis bairdi

56a Pharyngeal teeth in lesser row stout; body depth goes 4.25 times in standard length - Notropis potteri

56b Pharyngeal teeth in lesser row thin; body depth goes about 4 times in standard length - Notropis blennius

57a Lateral stripe diffuse - Notropis shumardi

57b Lateral stripe distinct - 58

58a Caudal spot separated from stripe by light space; pharyngeal teeth in 1 row (4-4) - Notropis atrocaudalis

58b Caudal spot, if present, attached to stripe; pharyngeal teeth in 2 rows - 59

59a Usually 8 anal fin rays - Notropis chalybaeus

59b Usually 7 anal fin rays - Notropis texanus

60a Last ray of dorsal fin about ½ the length of the longest; interradial membranes of dorsal fin with melanophores (weak or lacking in female and young of C. proserpina) - 61

60b Last ray of dorsal fin much less than ½ the length of the longest; interradial membranes of dorsal fin without melanophores (except along the edge of rays or forming a dash on the anterior two membranes) - 63

61a Tubercles on head of dominant males larger on snout than on occiput; a distinct black median stripe from the chin to the isthmus; snout length greater than upper jaw length - Cyprinella proserpina

61b Tubercles on head of dominant males larger on occiput than on snout; the black median stripe on chin extends no farther posteriorly than below the eye; upper jaw length greater than snout length - 62

62a Mouth slightly subinferior; head blunt and rounded; snout length plus upper jaw length 17% or less of standard length; body more slender, distance between dorsal and anal fin origins 24 to 29% of standard length (higher percentages for adult males, lower percentages for young females) - Cyprinella lepida

62b Mouth more terminal; head sharp and compressed; snout length plus upper jaw length 17% or more of standard length; body usually deeper, distance between dorsal and anal fin origins 26 to 36% of standard length (higher percentages for adult males, lower percentages for young females) - Cyprinella lutrensis

63a Lateral line incomplete; dark dash on proximal ⅓ of first 2 dorsal fin membranes - Notropis maculatus

63b Lateral line complete; no pronounced dark markings on dorsal fin membranes - 64

64a Lateral line scales markedly elevated anteriorly (higher than wide), their height 2 to 5 times their width ; usually 8 anal fin rays; pharyngeal teeth 4-4 - 65

64b Lateral line scales not markedly elevated anteriorly, their height 1 to 2 times their width; usually 7 anal fin rays; pharyngeal teeth 4-4 or 1,4-4,1 - 66

65a Body dark, with pronounced dark lateral stripe; dorsal fin height goes 2.1 or more times in predorsal length - Notropis volucellus

65b Body light, with predorsal spot most prominent color mark; dorsal fin height goes 2.0 or fewer times in predorsal length - Notropis buchanani

66a Upper sides of body with scattered, large melanophores - Notropis chihuahua

66b Upper sides of body without scattered, large melanophores - 67

67a Eye small, shorter than snout and contained about 4 times in head length - 68

67b Eye larger, equal to or longer than snout and contained 3.5 or fewer times in head length - 69

68a Fins not falcate, 1st anal fin ray less than twice as long as last; caudal peduncle depth about ½ greatest body depth (measured over curve) - Notropis sabinae

68b Fins falcate, 1st anal fin ray more than twice as long as last; caudal peduncle depth about ⅓ greatest body depth (measured over curve) - Notropis girardi

69a Depressed dorsal fin longer than head; distance from corner of mouth to posterior end of maxillary about equal to distance from corner of mouth to tip of mandible - Hybopsis amnis

69b Depressed dorsal fin shorter than head; distance from corner of mouth to posterior end of maxillary much less than distance from corner of mouth to tip of mandible - 70

70a Lateral stripe composed of a series of doubled dashes; dorsal base with two distinct black dashes separated by a clear space when viewed from above - Notropis stramineus

70b Lateral stripe solid, not composed of a series of doubled dashes, dorsal base without distinct black dashes separated by a clear space when viewed from above - 71

71a Pharyngeal teeth 1,4-4,1; lateral line below lateral stripe between pectoral and pelvic fins; lateral stripe composed of scattered melanophores - Notropis braytoni

71b Pharyngeal teeth 4-4; lateral line never below lateral stripe; lateral stripe solid - Notropis atrocaudalis

KEY TO CYPRINODONTIDAE

1a Distance from origin of dorsal fin to end of hypural plate more than distance from origin of dorsal to anterior nostril - Cyprinodon variegatus

1b Distance from origin of dorsal fin to end of hypural plate less than the distance from origin of dorsal to anterior nostril - 2

2a Abdomen fully scaled - 3

2b Abdomen naked anterior to pelvics - 5

3a Lateral scale rows 26 to 27; lateral blotches of female deeper than long; dark terminal caudal bar of adult males about ¼ of caudal depth - Cyprinodon eximius

3b Lateral scale rows 24 or 25; lateral blotches of female longer than deep; dark terminal caudal bar of adult males about ⅓ of caudal length - 4

4a Dorsal speckled at base; basal exposed part of lateral scales darker than edge - Cyprinodon elegans

4b Dorsal unicolor; lateral scales evenly colored - Cyprinodon bovinus

5a Caudal peduncle depth less than distance from snout to back of eye; in adults greatest body depth contained more than 2.5 times in standard length - Cyprinodon rubrofluviatilis

5b Caudal peduncle depth more than distance from snout to back of eye; in adults greatest body depth contained less than 2.5 times in standard length - Cyprinodon pecosensis

KEY TO DASYATIDAE

- Dasyatis sabina

KEY TO DORADIDAE

1a Lateral body surface with whitish stripes - Platydoras armatulus

1b Body covered with whitish spots - Agamyxis pectinifrons

KEY TO ELASSOMATIDAE

- Elassoma zonatum

KEY TO ELEOTRIDAE

1a Fewer than 40 scale rows; maxillary reaching anterior margin of orbit - Dormitator maculatus

1b More than 50 scale rows; maxillary reaching posterior margin of pupil - 2

2a Teeth on vomer - Gobiomorus dormitor

2b No teeth on vomer; preopercle with a posterio-ventrally directed spine - 3

3a Dorsal fin soft rays 12; 10 anal fin soft rays; scales cycloid; about 100 lateral scale rows - Erotelis smaragdus

3b Dorsal fin soft rays 9; 9 anal fin soft rays; ctenoid scales posteriorly; fewer than about 70 lateral scale rows - Eleotris amblyopsis

KEY TO ELOPIDAE

- Elops saurus

KEY TO ENGRAULIDAE

1a Twenty three to 31 anal fin rays; 11 to 12 pectoral fin rays - Anchoa mitchilli

1b Eighteen to 23 anal fin rays; 13 to 17 pectoral fin rays - Anchoa hepsetus

KEY TO ESOCIDAE

1a Opercles with scales on dorsal half only - Esox lucius

1b Opercles with scales covering most of ventral half - 2

2a Branchiostegal rays 11 to 13; fewer than 115 scale rows along body - Esox americanus

2b Branchiostegal rays 14 to 17; more than 120 scale rows along body - Esox niger

KEY TO FUNDULIDAE

1a Distance from origin of dorsal fin to end of hypural plate less than distance from origin of dorsal fin to preopercle or occasionally about equal to that distance; more than 30 longitudinal scale rows - 2

1b Distance from origin of dorsal fin to end of hypural plate more than distance from origin of dorsal fin to preopercle; 30 or fewer longitudinal scale rows - 11

2a More than 40 longitudinal scale rows; gill slit not extending dorsal to uppermost pectoral fin ray - 3

2b Fewer than 40 longitudinal scale rows; gill slit extending dorsal to uppermost pectoral fin ray - 4

3a Lateral scales large; usually 42 to 50 scale rows in lateral series (modally 47); breeding males with red on fins - Fundulus zebrinus

3b Lateral scales small; usually 47 to 60 scale rows in lateral series (modally 53); breeding males with orangish-yellow fins - Fundulus kansae

4a Body with a distinct dark lateral band - 5

4b Body without a distinct dark lateral band - 6

5a Spots on body distinct, color resembles lateral band - Fundulus olivaceus

5b Spots on body diffuse, color resembles back coloration - Fundulus notatus

6a Eye goes more than 1.5 times in snout; body with about 10 dark bars, the last with dark spot dorsally - Fundulus similis

6b Eye goes fewer than 1.5 times in snout; body barred or not, but never with a dark spot on dorsal part of caudal peduncle - 7

7a A dark subocular bar; most prominent dark spots on body arranged in more than 2 lengthwise stripes - Fundulus blairae

7b No dark subocular bar; body mottled, barred or irregularly spotted - 8

8a Dorsal fin originating posterior to anal fin origin; fewer than 15 scale rows from pelvic origin to isthmus - 9

8b Dorsal fin originating anterior to anal fin origin; more than 15 scale rows from pelvic fin origin to isthmus - 10

9a Large black spots on body arranged in 2 irregular rows; 11 to 13 anal fin rays - Fundulus jenkinsi

9b Dark spots on body absent or small and not in rows; usually 10 anal fin rays - Fundulus chrysotus

10a Predorsal stripe absent or not reaching occiput - Fundulus grandis

10b Predorsal stripe reaching occiput; no noticeable cross-hatched pattern; dark markings on scales not concentrated at posterior edge - Fundulus pulvereus

11a Body barred; body depth goes 3 times in standard length; fewer than 10 dorsal fin rays - Adinia xenica

11b Body not barred; body depth goes 3.5 times or more in standard length; 10 or more dorsal fin rays - 12

12a Conspicuous lateral stripe extending through eye to snout; body depth goes 4.5 to 5 times in standard length - Lucania goodei

12b No distinct lateral stripe; body depth goes 3.5 to 4 times in standard length - Lucania parva

KEY TO GERREIDAE

1a Preopercle strongly serrate; 12 or more gill rakers on lower limb of 1st gill arch - Diapterus auratus

1b Preopercle entire (or with only a few small serrations at angle); 9 or fewer gill rakers on lower limb of 1st gill arch - 2

2a Nine gill rakers on lower limb of 1st gill arch; spinous dorsal fin distinctly tri-colored (dusky at base, clear in middle, jet black at tip) - Eucinostomus melanopterus

2b Eight gill rakers on lower limb of 1st gill arch; spinous dorsal fin not tri-colored - Eucinostomus argenteus

KEY TO GOBIIDAE

1a Body long and slender; body depth goes about 7 times in standard length - Gobioides broussonetii

1b Body short and stout; body depth goes fewer than 7 times in standard length - 2

2a Upper pectoral fin rays free from membrane; tongue notched - Bathygobius soporator

2b Upper pectoral fin rays joined to membrane; tongue indented but not notched - 3

3a Body naked - 4

3b Body mostly scaled - 5

4a Usually 12 (11 to 13) 2nd dorsal fin rays; usually 10 (9 to 11) anal fin rays; pelvic length goes 1.2 to 1.5 times into distance from pelvic fin base to anal fin origin - Gobiosoma robustum

4b Usually 13 (12 to 14) 2nd dorsal fin rays; usually 11 (10 to 12) anal fin rays; pelvic length goes 1.6 to 2.0 times into distance from pelvic fin base to anal fin origin - Gobiosoma bosc

5a Second dorsal fin rays 15 to 16 ; 16 to 17 anal fin rays; dark brown spots on body; 2 or 3 dark vertical bars below 2nd dorsal fin - Microgobius gulosus

5b Second dorsal fin rays 11 to 14; 11 to 16 anal fin rays - 6

6a Second dorsal fin rays 14; 15 anal fin rays; more than 60 scales rows in lateral series - Gobionellus oceanicus

6b Second dorsal fin rays 11 to 12; 11 to 13 anal fin rays - 7

7a Scales small, more than 70 rows in lateral series - Awaous banana

7b Scales large, about 29 to 40 rows in lateral series - 8

8a Patch of scales on upper margin of opercle; 2 dark spots on caudal fin base - Evorthodus lyricus

8b No patch of scales on upper margin of opercle - 9

9a Second dorsal fin rays 11; 12 anal fin rays - Ctenogobius boleosoma

9b Second dorsal fin rays 12; 13 anal fin rays - 10

10a Upper membranes of dorsal fins clear or dusky but without distinct blackened margins - 11

10b Upper membranes of dorsal fins with distinct blackened margins - Gobionellus atripinnis

11a Canine teeth present on lower jaw - Ctenogobius stigmaticus

11b No canine teeth present on lower jaw - Ctenogobius shufeldti

KEY TO HAEMULIDAE

1a Preopercle strongly serrate, with anteriorly directed serrations on the lower margin; 2 enlarged spines at angle; 12 dorsal fin spines - Conodon nobilis

1b Preopercle moderately, or not at all, serrate, with no anterior pointing serrations; 13 dorsal fin spines - Pomadasys crocro

KEY TO HIODONTIDAE

- Hiodon alosoides

KEY TO ICTALURIDAE

1a Eyes absent; skin without pigment - 2

1b Eyes present; skin pigmented - 3

2a No teeth on jaws; lips at corner of mouth thin - Trogloglanis pattersoni

2b Well developed teeth on jaws; lips at corner of mouth thick - Satan eurystomus

3a Adipose fin joined to the caudal fin or separated from it by no more than a shallow notch - 4

3b Adipose fin free at tip, not joined to caudal fin - 5

4a Jaws nearly equal, mouth terminal; pectoral fin spine not serrated; dark axial streak conspicuous; dorsal, anal and caudal fins not dark edged; lower lip and chin not heavily speckled with dark pigment - Noturus gyrinus

4b Lower jaw included (underslung), mouth sub-terminal; pectoral spine serrated; axial streak inconspicuous; dorsal, anal and caudal fins with dark edges; lower lip and chin heavily speckled with dark pigment - Noturus nocturnus

5a Premaxillary band of teeth on upper jaw with a lateral backward extension on each side; head depressed - Pylodictis olivaris

5b Premaxillary band of teeth on upper jaw without a lateral backward extension on each side; head rounded - 6

6a Caudal fin rounded or shallowly emarginate; anal fin rays (including all rudiments) 17 to 27 - 7

6b Caudal fin deeply forked; anal fin rays (including all rudiments) 22 to 36 - 8

7a Anal fin rays 17 to 23; caudal fin square or slightly emarginate; chin barbels blackish; eye goes into snout length 2.4 or fewer times - Ameiurus melas

7b Anal fin rays 24 to 27; caudal fin rounded; chin barbels whitish; eye goes into snout length 2.6 or more times - Ameiurus natalis

8a Anal fin rays 30 to 36 - Ictalurus furcatus

8b Anal fin rays 22 to 29 - 9

9a Anal fin rays 27 to 29; pectoral fin spine goes less than 5 times into standard length - Ictalurus punctatus

9b Anal fin rays 22 to 26; pectoral fin spine goes more than 5 times into standard length - 10

10a Anal fin rays 23 to 26; pectoral spine length much more than caudal peduncle depth - Ictalurus lupus

10b Anal fin rays 22 to 25; pectoral spine length about equal to caudal peduncle depth - Ictalurus sp.

KEY TO LEPISOSTEIDAE

1a Large teeth in upper jaw in 2 rows on each side - Atractosteus spatula

1b Large teeth in upper jaw in 1 row on each side - 2

2a Beak long and narrow, its least width goes about 12 to 20 times in length; snout more than ⅔ of head length - Lepisosteus osseus

2b Beak short and blunt, its least width goes about 5 to 7 times in length; snout less than ⅔ of head length - 3

3a Fifty nine to 63 lateral line scales; 50 to 54 predorsal scales; 38 to 44 scale rows around body - Lepisosteus platostomus

3b Fifty four to 57 lateral line scales; 46 to 59 predorsal scales; 32 to 38 scale rows around body - Lepisosteus oculatus

KEY TO LORICARIIDAE

1a Dorsal fin short with 9 or fewer rays - Hypostomus sp.

1b Dorsal fin long with 10 or more rays - 2

2a Light spots on a dark background; ventral surface with white vermiculations wider than dark - Pterygoplichthys anisitsi

2b Dark spots on a light background - 3

3a Discrete spots on ventral surface; posterior sides of body without chevrons of coalesced spots - Pterygoplichthys multiradiatus

3b Dark spots forming extensive vermiculations on sides and ventral surface - Pterygoplichthys disjunctivus

KEY TO MEGALOPIDAE

- Megalops atlanticus

KEY TO MORONIDAE

1a Dorsal fins united at base; 2nd and 3rd anal fin spines approximately equal in length; no teeth on tongue; 9 to 10 anal fin soft rays; stripes along sides usually sharply broken and offset above front of anal fin - Morone mississippiensis

1b Dorsal fins separated; 2nd anal fin spine much shorter than 3rd; base of tongue with teeth; 11 to 13 anal fin soft rays; stripes along sides usually continuous - 2

2a Body depth goes less than 3 times in standard length; teeth in single patch on back of tongue - Morone chrysops

2b Body depth goes more than 3 times in standard length; teeth in 2 parallel patches on back of tongue - Morone saxatilis

KEY TO MUGILIDAE

1a Lower jaw rounded, without a symphyseal knob; lower limb of 1st gill arch with 17 to 20 gill rakers; no adipose eyelid; scales ctenoid - Agonostomus monticola

1b Lower jaw angular, with a prominent symphyseal knob; lower limb of 1st gill arch with 25 to 60 gill rakers; adipose eyelid well developed in adults; scales cycloid in young, ctenoid in adults - 2

2a Soft dorsal and anal fins with few scales; sides with longitudinal dark stripes along the scale rows; usually 8 (rarely 7 or 9) anal fin soft rays; usually 41 lateral line scales - Mugil cephalus

2b Soft dorsal and anal fins with many scales; sides without longitudinal dark stripes along the scale rows; usually 9 anal fin soft rays; usually 38 lateral line scales - Mugil curema

KEY TO OPHICHTHIDAE

- Myrophis punctatus

KEY TO PARALICHTHYIDAE

1a Lateral line with no high arch over the pectoral fin on the ocular side - 2

1b Lateral line highly arched over the pectoral fin on the ocular side - Paralichthys lethostigma

2a Upper jaw reaching to below the middle of eye; jaws equal; greatest body depth ½ or less of standard length - Citharichthys spilopterus

2b Upper jaw reaches to below front of eye; jaw on blind side larger than jaw on eyed side; greatest body depth greater than ½ of standard length - Etropus crossotus

KEY TO PERCIDAE

1a Preopercle strongly serrate; upper jaw extending to below the middle of the eye or farther - 2

1b Preopercle smooth or weakly serrated; upper jaw not extending as far as to below middle of eye - 4

2a Anal fin soft rays 6 to 8; no canine teeth - Perca flavescens

2b Anal fin soft rays 12 to 13; canine teeth strong - 3

3a Cheeks well scaled; 17 to 19 dorsal fin soft rays; 5 or 6 pyloric caecae - Sander canadensis

3b Cheeks sparsely scaled; 19 to 22 dorsal fin soft rays; 3 or 4 pyloric caecae - Sander vitreus

4a Belly naked; body depth contained in standard length more than 7 times - 5

4b Belly scaled (a narrow naked band may be present on midline); body depth contained in standard length less than 7 times - 6

5a Scales restricted to lateral line region; lateral blotches longer than deep - Ammocrypta clara

5b Scales not restricted to lateral line region; lateral blotches deeper than long - Ammocrypta vivax

6a More than 77 scales in lateral line; snout conical extending beyond upper lip - 7

6b Less than 77 scales in lateral line; snout less conical, not extending beyond upper lip - 9

7a Lateral bars wide, 9 to 10 whole bars; mid-bars between whole bars short, about ½ the length of the whole bars - 8

7b Lateral bars thin, 14 to 16 whole bars (usually 15); mid-bars between whole bars long, about equal to length of whole bars - Percina macrolepida

8a Vertical bars on sides of body with obvious constrictions medially; bars expanded dorso- and ventrolaterally; breeding males with black on breast and also the pelvic and anal fins - Percina carbonaria

8b Vertical bars on sides of body equal thickness throughout length, without obvious constrictions medially; breeding males without black on breast, pelvic or anal fins - Percina caprodes

9a Sides with large black rectangular blotches; midline of belly with a series of enlarged scales or naked - 10

9b Sides without large black rectangular blotches; scales on belly normal - 14

10a Less than 60 scales in lateral line; upper lip connected to snout by a narrow frenum - Percina shumardi

10b More than 60 lateral line scales; upper lip connected to snout by a broad frenum - 11

11a Nape naked; upper jaw reaches to pupil of eye - Percina maculata

11b Nape scaled; upper jaw reaches to no more than anterior ⅓ of eye - 12

12a Preopercular serrae 5 or more - Percina sciera

12b Preopercular serrae 0 to 3 - 13

13a Usually 10 anal rays; short snout and head; head length contained in standard length more than 4.5 times - Percina apristis

13b Usually 9 anal rays; long snout and head; head length contained in standard length less than 4 times - Percina phoxocephala

14a Lateral line very short, fewer than 6 scales with pores - 15

14b More than 6 pored lateral line scales - 16

15a Dorsal fin spines 6 (occasionally 7); anal fin spine1 - Etheostoma fonticola

15b Dorsal fin spines 8; anal fin spines 2 - Etheostoma proeliare

16a Pectoral fin longer than head, reaching beyond anus; head angular, profile in front of eye more than 45 degrees - Etheostoma histrio

16b Pectoral fin shorter than head, not reaching anus; head profile rounded, profile in front of eye less than 45 degrees - 17

17a Lateral line with a slight upward curve anteriorly - 18

17b Lateral line straight - 19

18a Infraorbital canal uninterrupted, 6 to 8 (usually 8) pores; breast unscaled; distance from snout to angle of gill cover equal to ½ of head length - Etheostoma gracile

18b Infraorbital canal interrupted with 2 to 4 pores in the anterior segment and usually 2 pores in the posterior segment; breast scaled; distance from snout to angle of gill cover greater than ½ of head length - Etheostoma fusiforme

19a Anal fin spine 1; body depth contained in standard length more than 5 times - Etheostoma chlorosoma

19b Anal fin spines 2; body depth contained in standard length less than 5 times - 20

20a Light longitudinal streak along lateral line; body in cross section nearly round - Etheostoma parvipinne

20b No light longitudinal streak along lateral line; body cross section oval - 21

21a Gill membranes rather widely joined across isthmus; a black spot at upper margin of pectoral fins - 22

21b Gill membranes hardly connected; no black spot on upper margin of pectoral fins - 23

22a No discrete red or yellow spots on side of body; vertical blotches on sides of body most distinct posteriorly - Etheostoma radiosum

22b Discrete red (in males) or yellow spots (in females) on side of body; vertical blotches on sides of body usually not prominent - Etheostoma artesiae

23a Infraorbital canal complete - Etheostoma asprigene

23b Infraorbital canal interrupted below eye - 24

24a Body bars 8 to 9; throat of males orange (lost in preservation) - Etheostoma spectabile

24b Body bars 10 to 12; throat of males blue or red (lost in preservation) - 25

25a Opercle naked or with only a few scales; more than 50 lateral line scales; throat blue or green in males (lost in preservation) - Etheostoma lepidum

25b Opercle heavily scaled; fewer than 50 lateral line scales; throat red in males (lost in preservation) - Etheostoma grahami

KEY TO PETROMYZONTIDAE

1a Disc large; length of disc 143 times in total length; cusps in posterior field not degenerate; adults with well-developed intestine - Ichthyomyzon castaneus

1b Disc small; length of disc 172 to 263 times in total length; cusps in posterior field degenerate; intestine not developed - Ichthyomyzon gagei

KEY TO POECILIIDAE

1a Origin of dorsal fin anterior to anal fin origin; intestinal canal long with many convolutions - 2

1b Origin of dorsal fin posterior to anal fin origin; intestinal canal short with few convolutions - 5

2a Dorsal fin rays 10 or more - 3

2b Dorsal fin rays fewer than 9 (usually 7 or 8) - Poecilia reticulata

3a Dorsal fin rays 12 to 14 - 4

3b Dorsal fin rays 10 to 12; dorsal fin base less than ½ predorsal length; dark spots on scales do not obscure diamond-shaped color pattern; only exists as females - Poecilia formosa

4a Dorsal fin base more than ½ predorsal length; dark spots on scales obscure diamond-shaped color pattern - Poecilia latipinna

4b Dorsal fin base approximately ½ predorsal length; no dark spots on scales, often a dark lateral stripe; males with greatly elongated lower caudal rays - Xiphophorus hellerii

5a Dorsal fin origin slightly behind anal fin origin; dark band on sides with vertical bars; large black spots near bases of dorsal and caudal fins of both sexes and on anal fin of females - Heterandria formosa

5b Dorsal fin origin well behind anal fin origin; no dark band on sides; median fins without large black spots near their bases - 6

6a Spines at tip of 3rd anal fin ray of male gonopodium (first enlarged ray) 1 to 3 times longer than wide - 7

6b Spines at tip of 3rd anal fin ray of male gonopodium 4 to 10 times longer than wide - 8

7a Dorsal fin rays 6 (rarely 7); distal end of the 4th fin ray of gonopodium in male parallel or curved in only a weak arch - Gambusia affinis

7b Dorsal fin rays 7; distal end of the 4th fin ray of gonopodium in male curved in a wide arch - Gambusia speciosa

8a Distal segments of anterior branch of 4th fin ray of gonopodium coalesced to elbow - Gambusia georgei

8b Distal segments of anterior branch of 4th fin ray of gonopodium not coalesced to elbow - 9

9a Dorsal fin rays 9 (rarely 10); predorsal stripe distinct and broad - Gambusia clarkhubbsi

9b Dorsal fin rays 7-8; predorsal stripe thin or absent - 10

10a Dorsal and anal fins without yellow pigmentation; dusky lateral stripe indistinct; mouth without dark markings and anal spot of females not restricted to area immediately around anus; pectoral fin of males with indentation, much deeper than widest pectoral fin ray - Gambusia heterochir

10b Dorsal and (in females) anal fins with yellow pigmentation (lost in preservation); dusky lateral stripe pronounced; mouth with dark markings or anal spot of females restricted to area immediately around anus; pectoral fin of males with slight indentation, shallower than widest pectoral fin ray - 11

11a Lateral stripe broad; caudal fin without prominent dark markings; markings on sides crescentric; tip of anterior branch of 4th ray of male gonopodium does not extend to tip of posterior branch - 12

11b Lateral stripe thin and threadlike; caudal fin with prominent dark markings; markings on sides rounded specks; tip of anterior branch of 4th ray of male gonopodium extends as far as tip of posterior branch - 14

12a Elbow of gonopodium composed of usually 4 fused segments; no dark markings around anus of mature females - Gambusia senilis

12b Elbow of gonopodium composed of usually 2 (rarely 3) fused segments; dark markings on anus of mature females - 13

13a Body deep, maximum body depth goes into standard length about 4 times in females; longest serra goes 1.2 times (usually ranges from 1.0 to 1.4) into width of segment on ray 4p of gonopodium; suborbital bar weak; chin bar faint; few crescentric lateral marks; predorsal streak weak to absent - Gambusia gaigei

13b Body slender, maximum body depth goes into standard length about 5 times in females; longest serra goes 1.7 times (usually ranges from 1.5 to 1.9) into width of segment on ray 4p of gonopodium; suborbital bar prominent; lateral stripe broad and conspicuous - Gambusia amistadensis

14a Postanal streak prominent (darker than markings on scale pockets); dark markings on mouth; median row of spots on caudal fin; median row of spots on dorsal fin; terminal hook on 4th and 5th rays of gonopodium angular at tip - Gambusia geiseri

14b Postanal streak weaker than markings on scale pockets; dusky or no markings on mouth; no prominent spots in middle of caudal fin; a subbasal row of spots on dorsal fin; terminal hooks on 4th and 5th rays of gonopodium rounded at tip - Gambusia nobilis

KEY TO POLYNEMIDAE

- Polydactylus octonemus

KEY TO POLYODONTIDAE

- Polyodon spathula

KEY TO PRISTIDAE

- Pristis pectinata

KEY TO SALMONIDAE

1a Lateral scale rows 120 to 140; basibranchial teeth absent; paired fins with a white border; no deep red to orangish slash on each side of throat along inner side of dentary bone; small spots heavily scattered along sides and caudal fin - Oncorhynchus mykiss

1b Lateral scale rows 150 to 180; basibranchial teeth usually present, but small or vestigial; paired fins uniformly brown or reddish but without a white border; deep red to orangish slash on each side of throat along inner side of dentary bone; large spots concentrated on caudal peduncle in adults - Oncorhynchus clarki

KEY TO SCIAENIDAE

1a Lower jaw projecting; 1 pair of enlarged canine teeth on upper jaw - 2

1b Upper jaw projecting or mouth terminal; no enlarged teeth - 3

2a Upper sides with well defined spots; 3rd and 4th dorsal fin spines the longest; membrane between soft dorsal and anal rays not scaled - Cynoscion nebulosus

2b Upper sides without spots; 1st and 2nd dorsal fin spines the longest; membrane between soft dorsal and anal rays scaled - Cynoscion arenarius

3a Lower jaw with 1 or more barbels - 4

3b Lower jaw without barbels - 5

4a Pectoral fin length about equal to the distance from the front of the eye to the opercular membrane - Micropogonias undulatus

4b Pectoral fin length about equal to the head length - Pogonias cromis

5a Mouth terminal; distance from anal fin origin to hypural plate much less than the distance from the anal fin origin to the pelvic fin origin - Bairdiella chrysoura

5b Mouth inferior; distance from anal fin origin to hypural plate equal to the distance from the anal fin origin to the pelvic fin origin - 6

6a Dark shoulder spot; more than 60 lateral line scales - Leiostomus xanthurus

6b No dark shoulder spot; fewer than 60 lateral line scales - 7

7a Dark spot on caudal peduncle above lateral line; upper jaw extends posterior to eye - Sciaenops ocellatus

7b No dark spot on caudal peduncle; upper jaw extends to below middle of eye - Aplodinotus grunniens

KEY TO SPARIDAE

1a More than 60 lateral line scales; a dark shoulder spot - Lagodon rhomboides

1b Fewer than 50 lateral line scales; no shoulder spot - Archosargus probatocephalus

KEY TO SYNGNATHIDAE

1a Median trunk ridge deflected ventrally at anus and continuous with inferior trunk ridge; 40 to 47 dorsal rays; obvious spiny projections on rings; brood pouch on males under belly - Microphis brachyurus

1b Median trunk ridge terminates at anus; 27 to 36 dorsal rays; lateral tail ridge with a slight discontinuity and then an upward swing posteriorly - 2

2a Snout short, 40 to 50% of head length; 27 to 36 dorsal fin rays; 15 to 17 trunk rings; 30 to 34 tail rings - Syngnathus scovelli

2b Snout long, 49 to 66% of head length; 33 to 36 dorsal fin rays; 19 to 21 trunk rings; 34 to 37 tail rings - Syngnathus louisianae

KEY TO TETRAODONTIDAE

- Sphoeroides parvus