Cyprinodon pecosensis

Pecos pupfish






Type Locality

Oxbow of Pecos River at Bitter Lake National Wildlife Refuge, 11.6 km east, 8 km north Roswell, Chaves County, New Mexico (Echelle and Echelle 1978).


Etymology/Derivation of Scientific Name

Cyprinodon – Greek meaning “toothed carps” (Edwards 1999); pecosensis – referring to the Pecos River (name suggested by R.R. Miller; Echelle and Echelle 1978).



Cyprinodon pecosensis Echelle and Echelle 1978:569.



Maximum size: 60 mm TL (Page and Burr 1991).


Coloration: From Sublette et al. (1990): nonbreeding males, juvenile males, and females brownish to greenish dorsolaterally with 7-9 dark lateral bars which expand into blotches; scattered blotches on lower sides; abdomen whitish. Dark cresent at base of caudal fin on females (Echelle and Echelle 1978); dark ocellus near the posterior base of dorsal fin, although Garrett (1980) noted that males in many populations of this species begin losing the dorsal ocellus long before the onset of sexual maturity. Young adult males have maintained the female color pattern when in small tanks with large males (Garrett 1980). Breeding males grayish blue to iridescent blue dorsolaterally; abdomen, cheeks, and opercles whitish; dorsal and anal fins black; black cresent at base of caudal fin; caudal fin with black terminal band; pectoral fins pale yellow (Echelle and Echelle 1978). The bright blue male nuptial coloration signals the possession of a territory, the ability of the owner to defend it, and the quality of that individual as a potential mate (Kodric-Brown 1977, 1983; Kodric-Brown and Nicoletto 1993).


Counts: Usually 2-3 mandibular pores (Page and Burr 1991).


Mouth position: Upturned (Page and Burr 1991). Mouth superior, lower jaw projecting (Sublette et al. 1990).


Body shape: Caudal peduncle depth more than distance from snout to back of head; in adults, greatest body depth contained less than 2.5 times in standard length; distance from origin of dorsal fin to end of hypural plate less than the distance from origin of dorsal to anterior nostril (Hubbs et al. 2008).


External morphology: Abdomen naked anterior to pelvics (Hubbs et al. 2008).


Internal morphology: Numerous tricuspid teeth on each jaw (Sublette et al. 1990).


Distribution (Native and Introduced)

U.S. distribution: Pecos River in Texas and New Mexico (Hubbs et al. 2008).


Texas distribution: Pecos River (Hubbs et al. 2008).


Abundance/Conservation status (Federal, State, NGO)

State Threatened (Texas; Garrett et al. 2002; Edwards et al. 2004; Hubbs et al. 2008); nearly extirpated in the state due to hybridization with the introduced sheepshead minnow (Cyprinodon variegatus). Listed as Endangered by the American Fisheries Society; status has declined since 1989; categories of threats: present or threatened destruction, modification, or reduction of habitat or range; and natural or anthropogenic factors that affect the existence of this species, including impacts of nonidigenous organisms, hybridization, competition, and/or predation (Jelks et al. 2008). Minckley et al. (1991) reported that C. pecosensis was endangered due to hybridization with C. variegatus, and habitat degradation and loss. Common, but hybridizing and possibly being replaced by introduced population of sheepshead minnow (C. variegatus; Page and Burr 1991). C. pecosensis was considered a species of special concern by the American Fisheries Society (Williams et al. 1989). C. pecosensis listed as threatened species by New Mexico in 1988 (Propst 1999; Garrett et al. 2002; Edwards et al. 2004); formerly classified as state endangered, Group II, in New Mexico (Sublette et al. 1990).


Cyprinodon pecosensis was most abundant fish in the Pecos River between New Mexico and Sheffield, Texas, in 1954 (Echelle and Conner 1989; Wilde and Echelle 1992; Echelle et al. 1997; Edwards 2001). In the early 1980s, non-native C. variegatus was inadvertently introduced into the Pecos River (Texas); since that time, abundance of C. pecosensis has declined and the species has been eliminated from the lower Pecos River as far upstream as Loving, New Mexico and replaced by a hybrid swarm (Echelle and Conner 1989; Wilde and Echelle 1992; Echelle et al. 1997; Edwards 2001; Edwards et al. 2004). C. variegatus x C. pecosensis specimens reported from two collection periods (1974-1994 and 2001-2002) in Independence Creek, Texas (Bonner et al. 2005). In 1985-1988, massive die-offs during golden alga (Prymnesium parvum) bloom occurred in Pecos River (Texas); following these events, C. variegatus x C. pecosensis hybrids were taken often from the freshwater reach were they had not been present in samples before, presumably as a result of the decimation of fishes normally inhabiting this reach which allowed this saline-oriented species to exist there (Rhodes and Hubbs 1992).


Habitat Associations

Macrohabitat: Species occurs in saline springs, gypsum sinkholes and desert streams (Allen 1980).


Mesohabitat: Although collected in low salinity waters, this species most typical in highly saline habitats that support relatively few species (Echelle and Echelle 1978; Allen 1980). Species tolerant to extremes in environmental factors (i.e. temperature, salinity, and dissolved oxygen; Albeit 1982).



Spawning season: May through September (Garrett 1981; Edwards 2001; Garrett et al. 2002); spawning peaks during June and July when water temperatures are 30°C or greater (Kodric-Brown 1977; Propst 1999; Edwards 2001). Albeit (1982) reported that peak spawning season ranged from May through August.


Spawning habitat: Territories established by males over rocky outcrops, submerged vegetation, and cobble scattered over silt substrates (Kodric-Brown 1983; Propst 1999). Females apparently prefer spawning over rocky outcrops (Kodric-Brown 1977; Propst 1999).


Spawning behavior: Males establish territories and attract females with a series of ritualized movements (Kodric-Brown 1983; Propst 1999). The period of courtship is shorter in the summer when competition for females is most intense (Kodric-Brown 1977; Propst 1999). Territories defended by males are smallest where density of fish is high; single male may mate with 4 or more females in one hour (Kodric-Brown 1981; Propst 1999). Females typically mate with several males over a period of days (Kodric-Brown 1977). In areas where fish density is low, territories are not established and dominance hierarchy and consort pair associations are the prevalent spawning behavior (Kodric-Brown 1988; Propst 1999). Species has the ability to alter reproductive traits in a changing environment (Garrett 1982; Propst 1999; Edwards 2001; Garrett et al. 2002).




Age/size at maturation: Less than one year at approximately 20 mm SL (Garrett et al. 2002).




Growth and Population structure: 


Longevity: Few adults survive over one year; winter populations consist primarily of fish born the previous summer (Kodric-Brown 1977; Garrett 1981; Garrett et al. 2002).


Food habits: Omnivorous, with a diatom-detritus mixture comprising bulk of diet; other food items included benthic animals, filamentous algae, macrophytes, sand, and seeds; sex, gut length, and habitat contributed to dietary differences among individual fish (Davis 1981). Cyprinodon pecosensis was found to be an opportunistic, omnivorous feeder; utilizing most abundant food item (diatoms; Albeit 1982).


Phylogeny and morphologically similar fishes

Cyprinodon pecosensis is a species of the C. variegatus complex (Liu 1969; Echelle and Echelle 1992; Echelle and Echelle (1998). C. pecosensis most closely resembles the Red River pupfish (C. rubrofluviatilis) in general appearance (Echelle and Echelle 1978). C. pecosensis most closely related to the Leon Springs pupfish (C. bovinus; Echelle and Echelle 1992; Propst 1999). C. pecosensis known to hybridize with C. variegatus (Echelle et al. 1987, 1997; Wilde and Echelle 1992, 1997; Rosenfield and Kodric-Brown 2003; Kodric-Brown and Rosenfield 2004; Rosenfield et al. 2004).


Cyprinodon pecosensis is similar to the Red River pupfish (C. rubrofluviatilis) but differs in that the caudal peduncle depth is more than distance from snout to back of eye and, in adults, the greatest body depth is contained less than 2.5 times in standard length; while in C. rubrofluviatilis the caudal peduncle depth is less than distance from snout to back of eye and, in adults, the greatest body depth is contained more than 2.5 times in standard length (Hubbs et al. 2008). C. pecosensis is similar to the Leon Springs pupfish (C. bovinus): the former species has a mostly unscaled belly; few dark blotches on lower side of female; no yellow in dorsal and caudal fins, narrow black bar on caudal fin edge of male; while the latter species has fully scaled belly; many small brown blotches on lower side of female; yellow in dorsal and caudal fins, wide black edge on caudal fin of male (Page and Burr 1991). See Echelle and Echelle (1978) for further comparison of differences among C. pecosensis, C. rubrofluviatilis and C. bovinus.


Host Records



Commercial or Environmental Importance

A Conservation Agreement initiated in 1999 is designed to reduce threats (habitat losses and hybridization with introduced C. variegatus) to Cyprinodon pecosensis and to establish populations in newly created habitats adjacent to the Pecos River (Edwards 2001; Garrett and Edwards 2001; Garrett et al. 2002; Edwards et al. 2004).


[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Cokendolpher 1980; Meffe and Vrijenhoek (1988); Echelle et al. (2005). Additional literatureCyprinodon pecosensis: Kodric-Brown and Hohmann (1990); Kodric-Brown and Mazzolini (1992); Kodric-Brown (1986, 1996, 1997).]



Albeit, P.S. 1982. The ecology of the Pecos pupfish, Cyprinodon pecosensis Echelle and Echelle in the lower Pecos drainage of New Mexico (Cyprinodontiformes; Cyprinodontidae). M.S. Thesis, Eastern New Mexico University, Portales.

Allen, A.W. 1980. Cyprinodon pecosensis (Echelle and Echelle), Pecos River pupfish.  pp. 499 in D. S. Lee et al., Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.

Bonner, T H., C. Thomas, C.S. Williams, and J.P. Karges. 2005. Temporal assessment of a west Texas stream fish assemblage. The Southwestern Naturalist 50(1):74-106.


Cokendolpher, J.C. 1980. Hybridization experiments with the genus Cyprinodon (Teleostei, Cyprinodontidae). Copeia (1):173-176.


Davis, J.R. 1981. Diet of the Pecos River pupfish, Cyprinodon pecosensis (Cyprinodontidae). The Southwestern Naturalist 25(4):535-540.


Echelle, A.A., and A.F. Echelle. 1978. The Pecos River pupfish, Cyprinodon pecosensis n. sp. (Cyprinodontidae), with comments on its evolutionary origin. Copeia 1978(4):569-582.


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: Cyprinodontidae): An ancestor-descendent hypothesis. Pp. 691-709 In: R.L. Mayden (ed.). Systematics, Historical Ecology, and North American Freshwater Fishes. Stanford University Press, Stanford, California.


Echelle, A.A. and A.F. Echelle. 1998. Evolutionary relationships of pupfishes in the Cyprinodon eximius complex (Atherinomorpha: Cyprinodontiformes). Copeia(4):852-865.


Echelle, A.A. and P.J. Conner. 1989. Rapid, geographically extensive genetic introgression after secondary contact between two pupfish species (Cyprinodon, Cyprinodontidae). Evolution 43(4):717-727.


Echelle, A.A., A.F. Echelle, and D.R. Edds. 1987. Population structure of four pupfish species (Cyprinodontidae, Cyprinodon) from the Chihuahuan Desert region of New Mexico and Texas – allozymic variation. Copeia 3:668-681.


Echelle, A.A., C.W. Hoagstrom, A.F. Echelle, and J.E. Brooks. 1997. Expanded occurrence of genetically introgressed pupfish (Cyprinodontidae: Cyprinodon pecosensis x C. variegatus) in New Mexico. Southwestern Naturalist 42(3):336-339.


Echelle, A.A., E.W. Carson, A.F. Echelle, R.A. Van Den Bussche, T.E. Dowling, and A. Meyer. 2005. Historical biogeography of the new-world pupfish genus Cyprinodon (Teleostei: Cyprinodontidae). Copeia 2:320-339.


Edwards, R.J. 1999. Ecological profiles for selected stream-dwelling Texas freshwater fishes II. Report to the Texas Water Development Board. 69 pp.


Edwards, R.J. 2001. Ecological profiles for selected stream-dwelling Texas freshwater fishes III. Report to the Texas Water Development Board. 59 pp.


Edwards, R.J., G.P. Garrett, and N.L. Allan. 2004. Aquifer dependent fishes of the Edwards Plateau region, Chapter 13. pp. 253-268 in: Mace, R.E., E.S. Angle, and W.F. Mulligan, III (Eds.). Aquifers of the Edwards Plateau. Texas Water Development Board. 360 pp.


Garrett, G.P. 1980. Unusual secondary sex characteristics in Cyprinodon or puzzling pupfish patterns. Proc. Desert Fish. Coun. 12:41-47.


Garrett, G.P. 1981. Variation in reproductive strategy in the Pecos pupfish, Cyprinodon pecosensis. Ph.D. dissertation, Univeristy of Texas at Austin, Austin. 202 pp.


Garrett, G.P. 1982. Variation in the reproductive traits of the Pecos pupfish, Cyprinodon pecosensis. American Midland Naturalist 108(2):355-363.


Garrett, G.P., and R.J. Edwards. 2001. Regional ecology and environmental issues in West Texas, Chapter 5. pp. 56-65 in: Mace, R.E., W.F. Mullican, Jr., and E.S. Angle (Eds.). Aquifers of West Texas. Texas Water Development Board.


Garrett, G.P., C. Hubbs, and R.J. Edwards. 2002. Threatened fishes of the world: Cyprinodon pecosensis Echelle and Echelle, 1978 (Cyprinodontidae). Environmental Biology of Fishes 65:366.


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. Texas Journal of Science, Supplement, 2nd edition 43(4):1-87.

Jelks, H.L., S.J. Walsh, N.M. Burkhead, S. Contreras-Balderas, E. Diaz-Pardo, D.A. Hendrickson, J. Lyons, N.E. Mandrak, F. McCormick, J.S. Nelson, S.P. Platania, B.A. Porter, C.B. Renaud, J.J. Schmitter-Soto, E.B. Taylor, and M.L. Warren, Jr. 2008. Conservation status of imperiled North American freshwater and diadromous fishes. Fisheries 33(8):372-407.

Kodric-Brown, A. 1977. Reproductive success and the evolution of breeding territories in pupfish (Cyprinodon pecosensis). Evolution 31(4):750-766.

Kodric-Brown, A. 1981. Variable breeding systems in pupfishes (genus Cyprinodon): Adaptations to changing environments. pp. 205-235 In: R.J. Naiman and D.L. Soltz (eds.). Fishes in North American Deserts, John Wiley and Sons, New York.

Kodric-Brown, A. 1983. Determinants of male reproductive success in pupfish (Cyprinodon pecosensis). Animal Behavior 31(1):128-137.

Kodric-Brown, A. 1986. Satellites and sneakers: opportunistic male breeding tactics in pupfish (Cyprinodon pecosensis). Behavioral Ecology and Sociobiology 19(6):425-432.

Kodric-Brown, A. 1988. Effect of population density, size of habitat and oviposition substrate on the breeding system of pupfish (Cyprinodon pecosensis). Ethology 77(1):28-43.

Kodric-Brown, A. 1997. Sexual selection, stabilizing selection and fluctuating asymmetry in two populations of pupfish (Cyprinodon pecosensis). Biological Journal of the Linnean Society 62:553-566.

Kodric-Brown, A. 1996. Role of male-male competition and female choice in the development of breeding coloration in pupfish (Cyprinodon pecosensis). Behavioral Ecology 7(4):431-437.

Kodric-Brown, A., and P. Mazzolini. 1992. The breeding system of pupfish, Cyprinodon pecosensis – effects of density and interspecific interactions with the killifish, Fundulus zebrinus. Environmental Biology of Fishes 35(2):169-176.

Kodric-Brown, A., and J.A. Rosenfield. 2004. Populations of Pecos pupfish (Cyprinodon pecosensis) differ in their susceptibility to hybridization with sheepshead minnow (C. variegatus). Behav. Ecol. Sociobiol. 56:116-123.

Kodric-Brown, A., and M.E. Hohmann. 1990. Sexual selection is stabilizing selection in pupfish (Cyprinodon pecosensis). Biological Journal of the Linnean Society 40(2):113-123.

Kodric-Brown, A. and P.F. Nicolette. 1993. The relationship between physical condition and social status in pupfish Cyprinodon pecosensis. Animal Behavior 46(6):1234-1236.

Liu, R.K. 1969. The comparative behavior of allopatric species (Teleostei – Cyprinodontidae: Cyprinodon).. Ph.D. Dissertation, Univ. California, Los Angeles. 185 pp.

Meffe, G.K., and R.C. Vrijenhoek. 1988. Conservation genetics in the management of desert fishes. Conservation Biology 2(2):157-169.


Minckley, W.L., G.K. Meffe, and D.L. Soltz. 1991. Conservation and management of short-lives fishes: the cyprinodontoids, Chapter 15. pp. 247-282 in: Minckley, W.L., and J.E. Deacon (Eds.). Battle Against Extinction: Native Fish Management in the American West. University of Arizona Press, Tucson, Arizona. 517 pp.


Page, L.M., and B.M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.

Propst, D.L. 1999. Threatened and endangered fishes of New Mexico. Technical Report No. 1. New Mexico Department of Game and Fish, Santa Fe, New Mexico. 84 pp.

Rhodes, K., and C. Hubbs. 1992. Recovery of Pecos River fishes from a red tide fish kill. The Southwestern Naturalist 37(2):178-187.

Rosenfield, J.A., and A. Kodric-Brown. 2003. Sexual selection promotes hybridization between Pecos pupfish, Cyprinodon pecosensis and sheepsheepshead minnow, C. variegatus. Journal of Evolutionary Biology 16(4):595-606.

Rosenfield, J.A., S. Nolasco, S. Lindauer, C. Sandoval, and A. Kodric-Brown. 2004. The role of hybrid vigor in the replacement of Pecos pupfish by its hybrids with sheepshead minnow. Conservation Biology 18(6):1589-1598.

Sublette, J.E., M.D. Hatch, and M. Sublette. 1990. The Fishes of New Mexico. University of New Mexico Press, Albuquerque. 393 pp.

Wilde, G.R., and A.A. Echelle. 1992. Genetic status of Pecos pupfish populations after establishment of a hybrid swarm involving an introduced congener. Trans. Amer. Fish. Soc. 121(3):277-286.

Wilde, G.R., and A.A. Echelle. 1997. Morphological variation in intergrade pupfish populations from the Pecos River, Texas, USA. Journal of Fish Biology 50(3):523-539.


Williams, J.E., J.E. Johnson, D.A. Hendrickson, S. Contreras-Balderas, J.D. Williams, M. Navarro-Mendoza, D.E. McAllister, and J.E. Deacon. 1989. Fishes of North America endangered, threatened, or of special concern: 1989. Fisheries 14(6):2-20.