Cyprinodon variegatus

sheepshead minnow

Type Locality

South Carolina (Lacepede 1803 in: Eschmeyer 2008).

Etymology/Derivation of Scientific Name

Cyprinodon, from Cyprinus, a genus of “minnows” and odious (stem odont), “tooth,” meaning minnows with teeth; variegates, Latin for “variegated, variously colored” (Boschung and Mayden 2003).

Synonymy

Cyprinodon variegatus Lacepede 1803:486; Hubbs et al. 1991:31.

      Cyprinodon variegatus variegatus Warren et al. 2000:18-19.

Characters

Maximum size: to 7.5 cm (Page and Burr 1991).

Coloration: 5-8 triangular shaped dark gray bars along silver-olive side, wide at top, narrow on lower side; green to blue-gray above; large dark brown blotches on rear half of upper side; white below; clear to light orange fins; breeding male is blue above, with wide dark gray bars along side (best developed at rear); brass-salmon cheek, breast, and belly; dusky orange fins; black edge on caudal fin (Page and Burr 1991).

Counts: Teeth compressed and with three cusps (Hubbs et al.1991); 22-28 lateral scales; 10-12 dorsal rays; 9-11 anal rays; 6-8 pelvic rays (Page and Burr 1991).

Body shape: Extremely deep bodied (Page and Burr 1991).

Mouth position: Blunt, terminal mouth (Ross 2001).

External morphology: Distance from origin of dorsal fin to end of hypural plate more than distance from origin of dorsal to anterior nostril; belly naked with more than 15 scale rows from pelvic origin to isthmus (Hubbs et al 1991); 18-22, usually 19-21, rakers on 1^st gill arch (Page and Burr 1991).

Distribution (Native and Introduced)

U.S. distribution: Primarily coastal waters on the Atlantic and Gulf coasts from Maine south through the Gulf of Mexico and the Caribbean to Venezuela; sometimes extends considerable distances upstream in coastal streams, especially in the Rio Grande (Hubbs et al 1991).

Texas distribution: Introduced populations exist at a number of localities in the Trans-Pecos region and in the San Antonio basin (Hubbs et al 1991). Warren et al. (2000) listed the following drainage units for distribution of Cyprinodon variegatus in the state: Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay (including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to mouth of Nueces River), Nueces River.

Abundance/Conservation status (Federal, State, NGO)

      Currently secure in the southern United States (Warren et al. 2000).

Habitat Associations

Macrohabitat: Coastal species found in relatively shallow brackish or fresh water (Johnson 1980). Large numbers of Cyprinodon variegatus noted along the shores of Texas bays (Allen 1942). In a study of marine fishes of Texas, Gunter (1945) showed that near the shore this species outnumbered all others, except Menidia beryllina peninsulae, and that it was most abundant on the shore and ponds of the Aransas Refuge and overwhelmingly so in the salt water ponds.

Mesohabitat: Locally may be very abundant where bottom is at least partially sandy, emergent vegetation lacking, and little current or wave action present; may establish populations in freshwater lakes containing relatively high dissolved solids (Johnson 1980). Collections have been made in salinities ranging from 0.0 – 35.6 ppt., but a preference was shown for salinities less than 20 ppt. (Kilby 1955). Tolerant of extreme changes in temperature and salinity.  Has been found along open shores of the Texas coast following fish-killing freezes (Simpson and Gunter 1956). Sheepshead minnows have one of the widest temperature tolerances known for a vertebrate species. The critical thermal maximum for fish acclimated at 30 C is 44.2 C, and minimum for fish acclimated at 5 C is 0.6 C (Bennett and Beitinger 1997).

Biology

Spawning season: Populations in Corpus Christi Pass, Texas, near Port Aransas, were found to spawn from April through October (De Vlaming et al. 1978). Collections from the Aransas National Wildlife Refuge, Texas, found males in breeding colors, “blue males”, from late April throughout July, but in decreasing numbers in the latter month (Gunter 1950). Gunter (1945) noted that in Texas populations, spawning covers a lengthy period and 18 mm young continue entering the population from June to September.

Spawning Habitat: Individuals nest in shallow water near the bank, in circular areas cleared by the male (Foster 1967).

Spawning behavior: During breeding season, males establish and vigorously defend territories (Foster 1967), a female enters and chooses a spot in the territory, then both settle onto the bottom of site, 8-10 eggs are deposited, and covered with sand, as eggs left on surface are readily eaten by other fishes. This is repeated six or seven times in a few minutes time period (Mettee and Beckham 1978).

Fecundity: About 8-10 eggs are deposited, and repeated 6-7 times in a period of a few minutes (Mettee and Beckham 1978).

Age at maturation: In one year or less (Foster 1967).

Migration: During freezes and cold parts of the year, this fish may be found away from shore in deeper water (Springer and Woodburn 1960). Gunter (1945) suggested that individuals move to deeper water in response to lower temperatures.

Growth and Population structure: In Texas, 924 specimens were collected measuring between 15-54 mm long. Fish from 15-47 mm long were present in February; approximate mode of length frequency cure was 43 mm and curve skewed strongly to the left; very few fish present below 20 mm long. This small group disappeared thereafter due to growth and in March through June the population ranged from 20-45 mm long with a mode at 38 mm. In July a large number of small fish entered the population with a distinct division into two groups; a large group measuring 40-54 mm long with a sharp mode at 43 mm and smaller fish measuring 15-35 mm long with a wide peak at 20-30 mm (Gunter 1950).

Longevity: Probably do not live beyond three years (Foster 1967).

Food habits: Omnivorous, feeding on organic detritus and algae (Gunter 1950; Simpson and Gunter 1956; Doherty 1987) as well as microcrustaceans, and dipteran larvae (Harrington and Harrington 1961). Sheepshead minnows will also remove external parasites from other fishes when the infected fish shows a distinctive, invitational posture (Able 1976), (i.e. Lucania parva, the rainwater killifish) as noted by Boschung and Mayden (2004). Species sometimes displays a “plowing” behavior, picking up mouthfuls of sand and expelling it at intervals, believed to be the means by which small plants or animals hidden in the bottom substrate are obtained (Foster 1967).

Phylogeny and morphologically similar fishes

The Red River pupfish (Cyprinodon rubrofluviatilis) and the Pecos pupfish (Cyprinodon pecosensis) have unscaled or partly scaled belly and yellow paired fins, head, belly on large male; the Leon Springs pupfish (Cyprinodon bovinus) has many small dark blotches on lower side, yellow on dorsal and caudal fins of male (Page and Burr 1991).

Echelle and Echelle (1992) regard Cyprinodon variegatus as the sister of a clade inclusive of C. rubrofluviatilis, and hypothesized that C. variegatus may be the ancestral species to four other species of Cyprinodon in inland drainages along the western Gulf of Mexico.

Host Records

Protozoa: Myxosporidia. Cestoda: Cyclophyllidean larva, Cystercoides, Glossocercus, Glossocercus cyprinodontis. Trematoda: Ascocotyle chandleri, Ascocotyle leighi, Ascocotyle leighi metacercaria. Nemata: Contracaecum, Contracaecum collieri. Acanthocephala: Atactorhynchus verecendus (Mayberry et al 2000).

Commercial or Environmental Importance

Johnson (1975) states that Cyprinodon variegatus may be most resistant of all fishes to variations in the chemical and physical environment; usually the predominant cyprinodontid in areas where virtually all other fish life is absent.

References

Able, K.W. 1976. Cleaning behavior in the cyprinodontid fishes: Fundulus majalis, Cyprinodon variegatus, and Lucania parva. Chesapeake Sci. 17(1):35-39

Bennett. W. . and T.L. Beitinger. 1997. Temperature tolerance of the sheepshead minnow Cyprinodon variegatus. Copeia 1997(I):77-87

Boschung, H.T., Jr. and R.L. Mayden. 2004. Fishes of Alabama. Smithsonian Books, Washington, D.C. 736 pp.

De Vlaming, V. L.A. Kuris, and F.R. Parker, Jr. 1978. Seasonal variation of reproduction and lipid reserves in some subtropical cyprinodontids. Trans Amer. Fish Soc. 107(3):464-472

Doherty, T.A. 1987. Fish assemblage structure of barrier island tidepools. Master's thesis, Univ. S. Mississippi, Hattiesburg.

Echelle, A.A., and A.F. Echelle. 1992. Mode and pattern of speciation in the evolution of inland pupfishes in the Cyprinodon variegatus complex (Teleostei: Cyprinodontiformes): an ancestor-descendant hypothesis. pp. 691-709 in Mayden, R. L. ed. 1992. Systematics, Historical Ecology, and North American Freshwater Fishes. Stanford University Press, Stanford, California, 969 pp.

Eschmeyer, W.N. Catalog of Fishes electronic version (23 April 2008): http://www.calacademy.org/research/ichthyology/catalog/fishcatsearch.html

Foster, N.R. 1967. Comparative studies on the biology of killifishes (Pisces: Cyprinodontidae). Ph.D. diss., Cornell Univ. Ithaca, N.Y., 369 pp.

Gunter, G. 1945. Studies on marine fishes of Texas. Pub. Inst. Mar. Sci., Univ. of Texas 1(1):1-190.

Gunter, G. 1950. Distributions and abundance of fishes on the Aransas National Wildlife Refuge, with life history notes. Publ. Inst. Mar. Sci., Univ. Tex. I(2):89-101.

Harrington, R.W., Jr., and E.S. Harrington. 1961. Food selection among fishes invading a high subtropical salt marsh: from onset of flooding through the progress of a mosquito brood. Ecology 42(4):646-666.

Hubbs, C., R.J. Edwards, and G.P. Garrett. 1991. An annotated checklist of the freshwater fishes of Texas, with keys to the identification of species. The Texas Journal of Science, Supplement 43(4):1-56

Johnson, W.E. 1975. Morphological variation and local distribution of Cyprinodon variegatus in Florida. Unpublished master’s thesis, Florida Technological University, Orlando, 163 pp.

Johnson, W.E. 1980. Cyprinodon variegates (Lacepède), Sheepshead minnow. pp. 504 in D. S. Lee, et al. Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.

Kilby, J.D. 1955. The fishes of two Gulf coastal marsh areas of Florida. Tulane Stud. Zool. 2(8):175-247.

Lacepède, B.G.E. 1803. Histoire naturelle des poissons. Hist. Nat. Poiss. v. 5: i-lxviii + 1-803 + index, Pls. 1-21.

Mayberry, L.F., A.G. Canaris, and J.R. Bristol. 2000. Bibliography of parasites and vertebrate host in Arizona, New Mexico, and Texas (1893-1984). University of Nebraska Harold W. Manter Laboratory of Parasitology Web Server pp. 1-100.

Mettee, M.F., and E.C. Beckham III. 1978. Notes on the breeding behavior, embryology and larval development of Cyprinodon variegatus Lacepède in aquaria. Tulane Stud. Zool. Bot. 20(3-4):137-148.

Page, L.M., and B.M. Burr. 1991. A Field Guide to Freshwater Fishes of North America, north of Mexico. Houghton Mifflin Company, Boston, 432 pp.

Ross, S.T. 2001. The Inland Fishes of Mississippi. University Press of Mississippi, Jackson. 624 pp.

Simpson D.G. and G. Gunter. 1956. Notes on habitats, systematic characters and life histories of Texas saltwater cyprinodontes. Tulane Stud. Zool. 4(4):115-134.

Springer, V.G., and K.D. Woodburn. 1960. An ecological study of the fishes of the Tampa Bay area. Fla. St. Bd. Conserv. Mar. Lab., Prof. Pap. Ser. 1:1-104.

Warren, M.L., Jr., B.M. Burr, S.J. Walsh, H.L. Bart, Jr., R.C. Cashner, D.A. Etnier, B.J. Freeman, B.R. Kuhajda, R.L. Mayden, H.W. Robison, S.T. Ross, and W.C. Starnes. 2000. Diversity, Distribution, and Conservation status of the native freshwater fishes of the southern United States. Fisheries 25(10):7-29.