A Virtual Museum on the State's Fish Biodiversity

Interactive key for identification of Texas Fishes

The text of the key provided here is taken verbatim from 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 added hyperlinks to make it easier to navigate and link from it to our species accounts.

If you already know the family of your specimen(s), use the alphabetized list of shortcuts below to jump to the key to its species. Otherwise, go first to our key to the families:

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ACHIRIDAE (American Soles | lenguados suelas | soles américaines)

ACIPENSERIDAE (Sturgeons | esturiones | esturgeons)

AMIIDAE (Bowfins | amias | poissons-castors)

ANGUILLIDAE (Freshwater Eels | anguilas de río | anguilles d’eau douce)

APHREDODERIDAE (Pirate Perches | percas pirata | perches-pirates)

ARIIDAE (Sea Catfishes | bagres marinos | poissons-chats marins)

ATHERINOPSIDAE (New World Silversides | charales y pejerreyes | poissons d’argent)

BELONIDAE (Needlefishes | agujones | aiguillettes)

CARANGIDAE (Jacks | jureles y pámpanos | carangues)

CARCHARHINIDAE (Requiem Sharks | tiburones gambuso | mangeurs d’hommes)

CATOSTOMIDAE (Suckers | matalotes | catostomes)

CENTRARCHIDAE (Sunfishes | lobinas | achigans et crapets)

CENTROPOMIDAE (Snooks | robalos | centropomes)

CHARACIDAE (Characins | carácidos | characins)

CICHLIDAE (Cichlids | tilapias y mojarras de agua dulce | cichlidés)

CLUPEIDAE (Herrings | sardinas | harengs)

CYPRINIDAE (Carps and Minnows | carpas y carpitas | carpes et ménés)

CYPRINODONTIDAE (Pupfishes | cachorritos | cyprinodontes)

DASYATIDAE (Whiptail Stingrays | rayas látigo | pastenagues)

DORADIDAE (Thorny Catfishes | bagres sierra | poissons-chats épineux)

ELASSOMATIDAE (Pygmy Sunfishes | solecitos | crapets-pygmées)

ELEOTRIDAE (Sleepers | guavinas | dormeurs)

ELOPIDAE (Tenpounders | machetes | guinées)

ENGRAULIDAE (Anchovies | anchoas | anchois)

ESOCIDAE (Pikes | lucios | brochets)

FUNDULIDAE (Topminnows | sardinillas | fondules)

GERREIDAE (Mojarras | mojarras | blanches)

GOBIIDAE (Gobies | gobios | gobies)

HAEMULIDAE (Grunts | burros y roncos | grogneurs)

HIODONTIDAE (Mooneyes | ojos de luna | laquaiches)

ICTALURIDAE (North American Catfishes | bagres de agua dulce | barbottes et barbues)

LEPISOSTEIDAE (Gars | pejelagartos | lépisostés)

LORICARIIDAE (Suckermouth Armored Catfishes | plecóstomas | loricariidés)

MEGALOPIDAE (Tarpons | sábalos | tarpons)

MORONIDAE (Temperate Basses | lobinas norteñas | bars)

MUGILIDAE (Mullets | lisas | muges)

OPHICHTHIDAE (Snake Eels | tiesos | serpents de mer)

PARALICHTHYIDAE (Sand Flounders | lenguados areneros | flétans de sable)

PERCIDAE (Perches | percas | perches et dards)

PETROMYZONTIDAE (Lampreys | lampreas | lamproies)

POECILIIDAE (Livebearers | topotes y espadas | poecilies)

POLYNEMIDAE (Threadfins | barbudos | capitaines)

POLYODONTIDAE (Paddlefishes | espátulas | spatules)

PRISTIDAE (Sawfishes | peces sierra | poissons-scies)

SALMONIDAE (Trouts and Salmons | truchas y salmones | truites et saumons)

SCIAENIDAE (Drums and Croakers | corvinas y berrugatas | tambours)

SPARIDAE (Porgies | plumas | dorades)

SYNGNATHIDAE (Pipefishes | peces pipa y caballitos de mar | hippocampes)

TETRAODONTIDAE (Puffers | botetes | sphéroïdes)

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 (Lampreys | lampreas | lamproies)

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 (Snake Eels | tiesos | serpents de mer)

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 (Freshwater Eels | anguilas de río | anguilles d’eau douce)

5a Body with plates; snout long and tubular - SYNGNATHIDAE (Pipefishes | peces pipa y caballitos de mar | hippocampes)

5b Body without plates; snout blunt - TETRAODONTIDAE (Puffers | botetes | sphéroïdes)

6a Five pairs of gill slits - 7

6b One pair of gill slits - 9

7a Gill slits dorsal to pectoral fins; body rounded - CARCHARHINIDAE (Requiem Sharks | tiburones gambuso | mangeurs d’hommes)

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

8a Snout elongate with sharp, saw-like teeth; no spines on dorsal surface - PRISTIDAE (Sawfishes | peces sierra | poissons-scies)

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

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 (Paddlefishes | espátulas | spatules)

11b Body with several bony scutes; snout not more than ⅔ of head length; 4 elongate barbels - ACIPENSERIDAE (Sturgeons | esturiones | esturgeons)

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

12b Scales cycloid; snout blunt; dorsal fin long, its origin anterior to the origin of the pelvic fin - AMIIDAE (Bowfins | amias | poissons-castors)

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 (American Soles | lenguados suelas | soles américaines)

14b Edges of preopercle not hidden by skin; both pectoral fins present - PARALICHTHYIDAE (Sand Flounders | lenguados areneros | flétans de sable)

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 (Characins | carácidos | characins)

18b More than 60 lateral line scales - SALMONIDAE (Trouts and Salmons | truchas y salmones | truites et saumons)

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 (Thorny Catfishes | bagres sierra | poissons-chats épineux)

20b No barbels; no spiked scutes; adipose fin with anterior spine - LORICARIIDAE (Suckermouth Armored Catfishes | plecóstomas | loricariidés)

21a Nostrils close together, posterior nostril without a barbel - ARIIDAE (Sea Catfishes | bagres marinos | poissons-chats marins)

21b Nostrils far apart, posterior nostril with a barbel - ICTALURIDAE (North American Catfishes | bagres de agua dulce | barbottes et barbues)

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 (Anchovies | anchoas | anchois)

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 (Herrings | sardinas | harengs)

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 (Mooneyes | ojos de luna | laquaiches)

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 (Tenpounders | machetes | guinées)

27b Mouth superior; last dorsal fin ray elongated - MEGALOPIDAE (Tarpons | sábalos | tarpons)

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 (Suckers | matalotes | catostomes)

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 (Carps and Minnows | carpas y carpitas | carpes et ménés)

29a Snout needle-shaped; lateral line very low - BELONIDAE (Needlefishes | agujones | aiguillettes)

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 (Pikes | lucios | brochets)

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 (Livebearers | topotes y espadas | poecilies)

32a Teeth conical and simple; 8 to 13 scale rows from pelvic origin to isthmus - FUNDULIDAE (Topminnows | sardinillas | fondules)

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

33a Anus anterior to pelvic fins; pelvic fins with more than 5 soft fin rays - APHREDODERIDAE (Pirate Perches | percas pirata | perches-pirates)

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 (Threadfins | barbudos | capitaines)

35b Pectoral fin entire - 36

36a Three anal fin spines; 4 stout dorsal fin spines - MUGILIDAE (Mullets | lisas | muges)

36b One anal fin spine; 4 to 8 slender dorsal fin spines - ATHERINOPSIDAE (New World Silversides | charales y pejerreyes | poissons d’argent)

37a Posterior part of lateral line with well developed spiny scutes; the 2 anal fin spines separated - CARANGIDAE (Jacks | jureles y pámpanos | carangues)

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 (Cichlids | tilapias y mojarras de agua dulce | cichlidés)

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 (Drums and Croakers | corvinas y berrugatas | tambours)

40b Three anal fin spines - 41

41a Two separate dorsal fins - CENTROPOMIDAE (Snooks | robalos | centropomes)

41b Dorsal fins continuous - HAEMULIDAE (Grunts | burros y roncos | grogneurs)

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 (Sleepers | guavinas | dormeurs)

43b Pelvic fins joined into a sucking disk - GOBIIDAE (Gobies | gobios | gobies)

44a Premaxillaries excessively protractile, their basal processes very long; a groove at the top of the cranium - GERREIDAE (Mojarras | mojarras | blanches)

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 (Porgies | plumas | dorades)

45b All teeth canines - 46

46a One or 2 anal fin spines, the 1st usually distinctly longer than the 2nd (if present) - PERCIDAE (Perches | percas | perches et dards)

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 (Temperate Basses | lobinas norteñas | bars)

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 (Pygmy Sunfishes | solecitos | crapets-pygmées)

48b Six to 13 dorsal fin spines; lateral line present; scales ctenoid; 6 or 7 branchiostegals - CENTRARCHIDAE (Sunfishes | lobinas | achigans et crapets)

 

KEY TO SPECIES OF FAMILY ACHIRIDAE (American Soles | lenguados suelas | soles américaines)

1a Right pectoral fin absent; 66 to 75 lateral line scales - Trinectes maculatus (Hogchoker | suela tortilla)

1b Right pectoral fin present; 75 to 85 lateral line scales - Achirus lineatus (Lined Sole | suela listada)

KEY TO SPECIES OF FAMILY ACIPENSERIDAE (Sturgeons | esturiones | esturgeons)

- Scaphirhynchus platorynchus (Shovelnose Sturgeon)

KEY TO SPECIES OF FAMILY AMIIDAE (Bowfins | amias | poissons-castors)

- Amia calva (Bowfin | poisson-castor)

KEY TO SPECIES OF FAMILY ANGUILLIDAE (Freshwater Eels | anguilas de río | anguilles d’eau douce)

- Anguilla rostrata (American Eel | anguila americana | anguille d’Amérique)

KEY TO SPECIES OF FAMILY APHREDODERIDAE (Pirate Perches | percas pirata | perches-pirates)

- Aphredoderus sayanus (Pirate Perch)

KEY TO SPECIES OF FAMILY ARIIDAE (Sea Catfishes | bagres marinos | poissons-chats marins)

1a Lower jaw with 4 barbels; pectoral and dorsal fins with long filaments - Bagre marinus (Gafftopsail Catfish | bagre bandera)

1b Lower jaw with 6 barbels; pectoral and dorsal fins without long filaments - Ariopsis felis (Hardhead Catfish | bagre boca chica)

KEY TO SPECIES OF FAMILY ATHERINOPSIDAE (New World Silversides | charales y pejerreyes | poissons d’argent)

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 (Brook Silverside | crayon d’argent)

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 (Rough Silverside | pejerrey rasposo)

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 (Texas Silverside)

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 (Inland Silverside | plateadito salado)

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 (Tidewater Silverside | plateadito playero)

KEY TO SPECIES OF FAMILY BELONIDAE (Needlefishes | agujones | aiguillettes)

- Strongylura marina (Atlantic Needlefish | agujón verde)

KEY TO SPECIES OF FAMILY CARANGIDAE (Jacks | jureles y pámpanos | carangues)

- Caranx hippos (Crevalle Jack | jurel común)

KEY TO SPECIES OF FAMILY CARCHARHINIDAE (Requiem Sharks | tiburones gambuso | mangeurs d’hommes)

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 (Finetooth Shark | tiburón dentiliso)

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 (Bull Shark | tiburón toro)

KEY TO SPECIES OF FAMILY CATOSTOMIDAE (Suckers | matalotes | catostomes)

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 (Blue Sucker | matalote azul)

3b Lip papillae long, extending forwards onto end of snout - Cycleptus sp. (Southeastern Blue Sucker)

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 (River Carpsucker | matalote chato)

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 (Bigmouth Buffalo)

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 (Black Buffalo | matalote negro)

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 (Smallmouth Buffalo | matalote boquín)

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 (Blacktail Redhorse)

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 (Golden Redhorse)

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 (Gray Redhorse)

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 (Mexican Redhorse | matalote chuime)

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 (Spotted Sucker)

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 (Lake Chubsucker)

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 (Creek Chubsucker)

KEY TO SPECIES OF FAMILY CENTRARCHIDAE (Sunfishes | lobinas | achigans et crapets)

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 (Largemouth Bass | lobina negra | achigan à grande bouche)

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 (Smallmouth Bass | lobina boca pequeña | achigan à petite bouche)

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 (Spotted Bass)

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 (Guadalupe Bass)

6a Teeth on tongue and pterygoids; supramaxilla longer than breadth of maxilla; maxillary width exceeds suborbital - Lepomis gulosus (Warmouth | mojarra golosa)

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 (Bantam Sunfish)

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 (Green Sunfish | pez sol)

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 (Redspotted Sunfish)

11a Palatine teeth present; opercular membrane dark to its margin - Lepomis auritus (Redbreast Sunfish)

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 (Dollar Sunfish)

12b Cheek scales 5 to 7; 13 to 15 pectoral fin rays; 38 to 49 lateral line scales; anal base nearly straight - Lepomis megalotis (Longear Sunfish | mojarra gigante | crapet à longues oreilles)

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 (Redear Sunfish | mojarra oreja roja)

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 (Orangespotted Sunfish)

14b Anal fins 10 to 12 soft rays; a dark spot on posterior part of dorsal fin; palatine teeth absent - Lepomis macrochirus (Bluegill | mojarra oreja azul | crapet arlequin)

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 (Rock Bass | mojarra piedrera | crapet de roche)

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 (Flier)

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 (White Crappie)

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 (Black Crappie | mojarra negra | marigane noire)

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 (Common Snook | robalo blanco)

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 (Smallscale Fat Snook | chucumite)

KEY TO SPECIES OF FAMILY CHARACIDAE (Characins | carácidos | characins)

- Astyanax mexicanus (Mexican Tetra | sardinita mexicana)

KEY TO SPECIES OF FAMILY CICHLIDAE (Cichlids | tilapias y mojarras de agua dulce | cichlidés)

1a Anal fin spines 5 or 6 - Cichlasoma cyanoguttatum (Rio Grande Cichlid | mojarra del norte)

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 (Redbelly Tilapia | tilapia panzaroja)

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 (Mozambique Tilapia | tilapia mosambica)

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 (Blue Tilapia | tilapia azul)

KEY TO SPECIES OF FAMILY CLUPEIDAE (Herrings | sardinas | harengs)

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 (Finescale Menhaden | sardina escamitas)

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 (Scaled Sardine | sardinita vivita escamuda)

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

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 (Gizzard Shad | sardina molleja | alose à gésier)

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 (Threadfin Shad | sardina maya)

KEY TO SPECIES OF FAMILY CYPRINIDAE (Carps and Minnows | carpas y carpitas | carpes et ménés)

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 (Common Carp | carpa común | carpe)

2b Upper jaw without barbels; 26 to 29 lateral line scales; pharyngeal teeth 4-4 - Carassius auratus (Goldfish | carpa dorada | carassin)

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 (Grass Carp | carpa herbívora)

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 (Mexican Stoneroller | rodapiedras mexicano)

5b Lower jaw length less than eye length; fewer than 60 lateral line scales - Campostoma anomalum (Central Stoneroller | rodapiedras del centro)

6a Premaxillaries not protractile; upper lip connected with skin of snout by a frenum - Rhinichthys cataractae (Longnose Dace | carpita rinconera | naseux des rapides)

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 (Golden Shiner | méné jaune)

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 (Rudd)

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 (Pugnose Minnow)

10b Mouth large and only moderately oblique; 2 pharyngeal teeth in lesser row - Semotilus atromaculatus (Creek Chub | mulet à cornes)

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 (Prairie Chub)

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

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

15b Lateral stripe distinct along side of body - Macrhybopsis marconis (Burrhead Chub)

16a Lateral stripe absent; 20 to 50 scales above lateral line with clusters of melanophores - Macrhybopsis aestivalis (Speckled Chub | carpa pecosa)

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

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 (Flathead Chub | carpa cabeza plana)

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

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 (Suckermouth Minnow | carpita chupadora)

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

19a More than 50 lateral line scales - Gila pandora (Rio Grande Chub | carpa del Bravo)

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 (Fathead Minnow | carpita cabezona | tête-de-boule)

21b Intestine short, forming a simple S-shaped loop; caudal spot separated from the longitudinal streak by a clear area - Pimephales vigilax (Bullhead Minnow | carpita cabeza de toro)

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 (Nueces Roundnose Minnow)

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 (Roundnose Minnow | carpa obispa)

26b Typically 37 or fewer lateral line scales - Dionda nigrotaeniata (Guadalupe Roundnose Minnow)

27a Double dashes present along lateral line canal; caudal spot wedge-shaped; prominent markings on dorsal scale pockets - Dionda diaboli (Devils River Minnow | carpa diabla)

27b Lateral line canal without double dashes; caudal spot rounded; no prominent markings on dorsal scale pockets - Dionda argentosa (Manantial Roundnose Minnow | carpa de manantial)

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

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 (Plains Minnow | carpa de las praderas)

30a Scales with 10 radii - Hybognathus nuchalis (Mississippi Silvery Minnow)

30b Scales with 8 radii - Hybognathus amarus (Rio Grande Silvery Minnow | carpa Chamizal)

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 (Blacktail Shiner | carpita colinegra)

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 (Proserpine Shiner | carpita río del norte)

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 (Plateau Shiner)

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 (Red Shiner | carpita roja)

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 (Striped Shiner)

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 (Silverband Shiner)

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 (Chub Shiner)

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 (River Shiner)

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 (Redfin Shiner)

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

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

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 (Texas Shiner | carpita texana)

45b Eye smaller, contained about 4 times in body depth (measured over curve); no black lips (may be dusky) - Notropis jemezanus (Rio Grande Shiner | carpita del Bravo)

46a Eye shorter than snout; underside of opercle light - Notropis oxyrhynchus (Sharpnose Shiner)

46b Eye longer than snout; underside of opercle gray - Notropis atherinoides (Emerald Shiner | méné émeraude)

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

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 (Taillight Shiner)

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 (Phantom Shiner | carpita de El Paso)

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 (Bluntnose Shiner | carpita chata)

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

53b Pectoral fin length goes fewer than 4 times in standard length; caudal spot faint - Notropis braytoni (Tamaulipas Shiner | carpita tamaulipeca)

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 (Smalleye Shiner)

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 (Red River Shiner)

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

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

57a Lateral stripe diffuse - Notropis shumardi (Silverband Shiner)

57b Lateral stripe distinct - 58

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

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

59a Usually 8 anal fin rays - Notropis chalybaeus (Ironcolor Shiner)

59b Usually 7 anal fin rays - Notropis texanus (Weed Shiner)

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 (Proserpine Shiner | carpita río del norte)

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 (Plateau Shiner)

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 (Red Shiner | carpita roja)

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

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 (Mimic Shiner | méné pâle)

65b Body light, with predorsal spot most prominent color mark; dorsal fin height goes 2.0 or fewer times in predorsal length - Notropis buchanani (Ghost Shiner | carpita fantasma)

66a Upper sides of body with scattered, large melanophores - Notropis chihuahua (Chihuahua Shiner | carpita chihuahuense)

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 (Sabine Shiner)

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 (Arkansas River Shiner | carpita del Arkansas)

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 (Pallid Shiner)

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 (Sand Shiner | carpita arenera | méné paille)

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 (Tamaulipas Shiner | carpita tamaulipeca)

71b Pharyngeal teeth 4-4; lateral line never below lateral stripe; lateral stripe solid - Notropis atrocaudalis (Blackspot Shiner)

KEY TO SPECIES OF FAMILY CYPRINODONTIDAE (Pupfishes | cachorritos | cyprinodontes)

1a Distance from origin of dorsal fin to end of hypural plate more than distance from origin of dorsal to anterior nostril - Cyprinodon variegatus (Sheepshead Minnow | bolín)

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 (Devils River Pupfish)

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 (Comanche Springs Pupfish | cachorrito de Manantiales Comanche)

4b Dorsal unicolor; lateral scales evenly colored - Cyprinodon bovinus (Leon Springs Pupfish)

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 (Red River Pupfish)

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 (Pecos Pupfish)

KEY TO SPECIES OF FAMILY DASYATIDAE (Whiptail Stingrays | rayas látigo | pastenagues)

- Dasyatis sabina (Atlantic Stingray | raya látigo de espina)

KEY TO SPECIES OF FAMILY DORADIDAE (Thorny Catfishes | bagres sierra | poissons-chats épineux)

1a Lateral body surface with whitish stripes - Platydoras armatulus (Southern Striped Raphael)

1b Body covered with whitish spots - Agamyxis pectinifrons (Whitebarred Catfish)

KEY TO SPECIES OF FAMILY ELASSOMATIDAE (Pygmy Sunfishes | solecitos | crapets-pygmées)

- Elassoma zonatum (Banded Pygmy Sunfish)

KEY TO SPECIES OF FAMILY ELEOTRIDAE (Sleepers | guavinas | dormeurs)

1a Fewer than 40 scale rows; maxillary reaching anterior margin of orbit - Dormitator maculatus (Fat Sleeper | naca)

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

2a Teeth on vomer - Gobiomorus dormitor (Bigmouth Sleeper | guavina bocón)

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 (Emerald Sleeper | guavina de concha)

3b Dorsal fin soft rays 9; 9 anal fin soft rays; ctenoid scales posteriorly; fewer than about 70 lateral scale rows - Eleotris amblyopsis (Largescaled Spinycheek Sleeper | dormilón oscuro)

KEY TO SPECIES OF FAMILY ELOPIDAE (Tenpounders | machetes | guinées)

- Elops saurus (Ladyfish | machete del Atlántico)

KEY TO SPECIES OF FAMILY ENGRAULIDAE (Anchovies | anchoas | anchois)

1a Twenty three to 31 anal fin rays; 11 to 12 pectoral fin rays - Anchoa mitchilli (Bay Anchovy | anchoa de caleta)

1b Eighteen to 23 anal fin rays; 13 to 17 pectoral fin rays - Anchoa hepsetus (Striped Anchovy | anchoa legítima)

KEY TO SPECIES OF FAMILY ESOCIDAE (Pikes | lucios | brochets)

1a Opercles with scales on dorsal half only - Esox lucius (Northern Pike | lucio | grand brochet)

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 (Redfin Pickerel | brochet d’Amérique)

2b Branchiostegal rays 14 to 17; more than 120 scale rows along body - Esox niger (Chain Pickerel | brochet maillé)

KEY TO SPECIES OF FAMILY FUNDULIDAE (Topminnows | sardinillas | fondules)

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 (Plains Killifish | sardinilla de las planicies)

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

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 (Blackspotted Topminnow)

5b Spots on body diffuse, color resembles back coloration - Fundulus notatus (Blackstripe Topminnow)

6a Eye goes more than 1.5 times in snout; body with about 10 dark bars, the last with dark spot dorsally - Fundulus similis (Longnose Killifish | sardinilla narigona)

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 (Western Starhead Topminnow)

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 (Saltmarsh Topminnow | sardinilla del Bravo)

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

10a Predorsal stripe absent or not reaching occiput - Fundulus grandis (Gulf Killifish | sardinilla del Pánuco)

10b Predorsal stripe reaching occiput; no noticeable cross-hatched pattern; dark markings on scales not concentrated at posterior edge - Fundulus pulvereus (Bayou Killifish | sardinilla mulata)

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

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 (Bluefin Killifish)

12b No distinct lateral stripe; body depth goes 3.5 to 4 times in standard length - Lucania parva (Rainwater Killifish | sardinilla de lluvia)

KEY TO SPECIES OF FAMILY GERREIDAE (Mojarras | mojarras | blanches)

1a Preopercle strongly serrate; 12 or more gill rakers on lower limb of 1st gill arch - Diapterus auratus (Irish Pompano | mojarra guacha)

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 (Flagfin Mojarra | mojarra de ley)

2b Eight gill rakers on lower limb of 1st gill arch; spinous dorsal fin not tri-colored - Eucinostomus argenteus (Spotfin Mojarra | mojarra plateada)

KEY TO SPECIES OF FAMILY GOBIIDAE (Gobies | gobios | gobies)

1a Body long and slender; body depth goes about 7 times in standard length - Gobioides broussonetii (Violet Goby | gobio violeta)

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 (Frillfin Goby | mapo aguado)

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 (Code Goby | gobio clave)

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 (Naked Goby | gobio desnudo)

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 (Clown Goby | gobio payaso)

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 (Highfin Goby | madrejuile flecha)

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 (River Goby | gobio de río)

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 (Lyre Goby | tismiche)

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

9a Second dorsal fin rays 11; 12 anal fin rays - Ctenogobius boleosoma (Darter Goby | madrejuile)

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 (Finescale Sleeper | guavina cristalina)

11a Canine teeth present on lower jaw - Ctenogobius stigmaticus (Marked Goby)

11b No canine teeth present on lower jaw - Ctenogobius shufeldti (Freshwater Goby)

KEY TO SPECIES OF FAMILY HAEMULIDAE (Grunts | burros y roncos | grogneurs)

1a Preopercle strongly serrate, with anteriorly directed serrations on the lower margin; 2 enlarged spines at angle; 12 dorsal fin spines - Conodon nobilis (Barred Grunt | ronco canario)

1b Preopercle moderately, or not at all, serrate, with no anterior pointing serrations; 13 dorsal fin spines - Pomadasys crocro (Burro Grunt | corocoro crocro)

KEY TO SPECIES OF FAMILY HIODONTIDAE (Mooneyes | ojos de luna | laquaiches)

- Hiodon alosoides (Goldeye | laquaiche aux yeux d’or)

KEY TO SPECIES OF FAMILY ICTALURIDAE (North American Catfishes | bagres de agua dulce | barbottes et barbues)

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 (Toothless Blindcat)

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

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 (Tadpole Madtom | chat-fou brun)

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 (Freckled Madtom)

5a Premaxillary band of teeth on upper jaw with a lateral backward extension on each side; head depressed - Pylodictis olivaris (Flathead Catfish | bagre pintontle)

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 (Black Bullhead | bagre torito negro)

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 (Yellow Bullhead | bagre torito amarillo | barbotte jaune)

8a Anal fin rays 30 to 36 - Ictalurus furcatus (Blue Catfish | bagre azul)

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 (Channel Catfish | bagre de canal | barbue de rivière)

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 (Headwater Catfish | bagre lobo)

10b Anal fin rays 22 to 25; pectoral spine length about equal to caudal peduncle depth - Ictalurus sp. (Channel Catfish | bagre de canal | barbue de rivière)

KEY TO SPECIES OF FAMILY LEPISOSTEIDAE (Gars | pejelagartos | lépisostés)

1a Large teeth in upper jaw in 2 rows on each side - Atractosteus spatula (Alligator Gar | catán)

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 (Longnose Gar | catán aguja | lépisosté osseux)

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 (Shortnose Gar)

3b Fifty four to 57 lateral line scales; 46 to 59 predorsal scales; 32 to 38 scale rows around body - Lepisosteus oculatus (Spotted Gar | catán pinto | lépisosté tacheté)

KEY TO SPECIES OF FAMILY LORICARIIDAE (Suckermouth Armored Catfishes | plecóstomas | loricariidés)

1a Dorsal fin short with 9 or fewer rays - Hypostomus sp. (Suckermouth Catfish)

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 (Southern Sailfin Catfish)

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 (Orinoco Sailfin Catfish | plecóstoma del Orinoco)

3b Dark spots forming extensive vermiculations on sides and ventral surface - Pterygoplichthys disjunctivus (Vermiculated Sailfin Catfish)

KEY TO SPECIES OF FAMILY MEGALOPIDAE (Tarpons | sábalos | tarpons)

- Megalops atlanticus (Tarpon | sábalo)

KEY TO SPECIES OF FAMILY MORONIDAE (Temperate Basses | lobinas norteñas | bars)

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 (Yellow Bass)

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 (White Bass | bar blanc)

2b Body depth goes more than 3 times in standard length; teeth in 2 parallel patches on back of tongue - Morone saxatilis (Striped Bass | lobina estriada | bar rayé)

KEY TO SPECIES OF FAMILY MUGILIDAE (Mullets | lisas | muges)

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 (Mountain Mullet | trucha de tierra caliente)

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 (Striped Mullet | lisa rayada)

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 (White Mullet | lisa blanca)

KEY TO SPECIES OF FAMILY OPHICHTHIDAE (Snake Eels | tiesos | serpents de mer)

- Myrophis punctatus (Speckled Worm Eel | tieso gusano)

KEY TO SPECIES OF FAMILY PARALICHTHYIDAE (Sand Flounders | lenguados areneros | flétans de sable)

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 (Southern Flounder | lenguado limpio)

2a Upper jaw reaching to below the middle of eye; jaws equal; greatest body depth ½ or less of standard length - Citharichthys spilopterus (Bay Whiff | lenguado pardo)

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 (Fringed Flounder | lenguado ribete)

KEY TO SPECIES OF FAMILY PERCIDAE (Perches | percas | perches et dards)

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 (Yellow Perch | perchaude)

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 (Sauger | doré noir)

3b Cheeks sparsely scaled; 19 to 22 dorsal fin soft rays; 3 or 4 pyloric caecae - Sander vitreus (Walleye | doré jaune)

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 (Western Sand Darter)

5b Scales not restricted to lateral line region; lateral blotches deeper than long - Ammocrypta vivax (Scaly Sand Darter)

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 (Bigscale Logperch | perca escamona)

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 (Texas Logperch)

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 (Logperch | fouille-roche zébré)

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 (River Darter)

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 (Blackside Darter)

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

12a Preopercular serrae 5 or more - Percina sciera (Dusky Darter)

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 (Guadalupe Darter)

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

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 (Fountain Darter | perca de manantial)

15b Dorsal fin spines 8; anal fin spines 2 - Etheostoma proeliare (Cypress Darter)

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

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 (Slough Darter)

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 (Swamp Darter)

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

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 (Goldstripe Darter)

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 (Orangebelly Darter)

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 (Redspot Darter)

23a Infraorbital canal complete - Etheostoma asprigene (Mud Darter)

23b Infraorbital canal interrupted below eye - 24

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

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 (Greenthroat Darter)

25b Opercle heavily scaled; fewer than 50 lateral line scales; throat red in males (lost in preservation) - Etheostoma grahami (Rio Grande Darter | perca del Bravo)

KEY TO SPECIES OF FAMILY PETROMYZONTIDAE (Lampreys | lampreas | lamproies)

1a Disc large; length of disc 143 times in total length; cusps in posterior field not degenerate; adults with well-developed intestine - Ichthyomyzon castaneus (Chestnut Lamprey | lamproie brune)

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

KEY TO SPECIES OF FAMILY POECILIIDAE (Livebearers | topotes y espadas | poecilies)

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 (Guppy | gupi)

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 (Amazon Molly | topote amazona)

4a Dorsal fin base more than ½ predorsal length; dark spots on scales obscure diamond-shaped color pattern - Poecilia latipinna (Sailfin Molly | topote velo negro)

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 (Green Swordtail | cola de espada)

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 (Least Killifish)

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 (Western Mosquitofish | guayacón mosquito)

7b Dorsal fin rays 7; distal end of the 4th fin ray of gonopodium in male curved in a wide arch - Gambusia speciosa (Tex-Mex Gambusia | guayacón de Nuevo León)

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

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 (0)

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 (Clear Creek Gambusia | guayacón de Clear Creek)

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 (Blotched Gambusia | guayacón del Bravo)

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 (Big Bend Gambusia | guayacón de Big Bend)

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 (Amistad Gambusia | guayacón de Amistad)

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 (Largespring Gambusia)

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 (Pecos Gambusia | guayacón del Pecos)

KEY TO SPECIES OF FAMILY POLYNEMIDAE (Threadfins | barbudos | capitaines)

- Polydactylus octonemus (Atlantic Threadfin | barbudo ocho barbas)

KEY TO SPECIES OF FAMILY POLYODONTIDAE (Paddlefishes | espátulas | spatules)

- Polyodon spathula (Paddlefish)

KEY TO SPECIES OF FAMILY PRISTIDAE (Sawfishes | peces sierra | poissons-scies)

- Pristis pectinata (Smalltooth Sawfish | pez sierra peine)

KEY TO SPECIES OF FAMILY SALMONIDAE (Trouts and Salmons | truchas y salmones | truites et saumons)

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 (Rainbow Trout | trucha arcoiris | truite arc-en-ciel)

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 (Mexican Golden Trout | trucha dorada mexicana)

KEY TO SPECIES OF FAMILY SCIAENIDAE (Drums and Croakers | corvinas y berrugatas | tambours)

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 (Spotted Seatrout | corvina pinta)

2b Upper sides without spots; 1st and 2nd dorsal fin spines the longest; membrane between soft dorsal and anal rays scaled - Cynoscion arenarius (Sand Seatrout | corvina arenera)

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 (Atlantic Croaker | gurrubata)

4b Pectoral fin length about equal to the head length - Pogonias cromis (Black Drum | tambor negro)

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 (Silver Perch | ronco amarillo)

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 (Spot | croca)

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 (Red Drum | corvineta ocelada)

7b No dark spot on caudal peduncle; upper jaw extends to below middle of eye - Aplodinotus grunniens (Freshwater Drum | roncador de agua dulce | malachigan)

KEY TO SPECIES OF FAMILY SPARIDAE (Porgies | plumas | dorades)

1a More than 60 lateral line scales; a dark shoulder spot - Lagodon rhomboides (Pinfish | xlavitia)

1b Fewer than 50 lateral line scales; no shoulder spot - Archosargus probatocephalus (Sheepshead | sargo chopa)

KEY TO SPECIES OF FAMILY SYNGNATHIDAE (Pipefishes | peces pipa y caballitos de mar | hippocampes)

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 (Opossum Pipefish | pez pipa culebra)

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 (Gulf Pipefish | pez pipa del Golfo)

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 (Chain Pipefish | pez pipa cadena)

KEY TO SPECIES OF FAMILY TETRAODONTIDAE (Puffers | botetes | sphéroïdes)

- Sphoeroides parvus (Least Puffer | botete xpú)