The Pecos pupfish (''Cyprinodon pecosensis'') is a species of pupfish in the family Cyprinodontidae. It is endemic to the

Pecos River The Pecos River ( es, Río Pecos) originates in north-central New Mexico and flows into Texas, emptying into the Rio Grande. Its headwaters are on the eastern slope of the Sangre de Cristo mountain range in Mora County north of Pecos, New Mexico ...

watershed in eastern New Mexico and western Texas in the United States.

Distribution and Habitat

Despite once existing throughout the Pecos River, ''C. pecosensis'' populations have become increasingly isolated due to significant portions of their native habitat being removed. Following the introduction of ''

Cyprinodon variegatus The sheepshead minnow or sheepshead pupfish (''Cyprinodon variegatus'') is a species of ray-finned fish in the family Cyprinodontidae, the pupfishes. It is found in salt marsh and estuary environments and is native to the eastern coasts of North ...

'' (sheepshead minnow), pure Pecos pupfish populations have been further isolated and largely exist in scattered sinkholes, man-made impoundments, and marshes. Its natural habitat includes springs, sinkholes, and pools of streams.

Introduction of ''Cyprinodon variegatus''

'' is thought to have been introduced during the early 1980s, presumably via bait-bucket dumping. Shortly after the introduction of ''C. variegatus'', ''C. variegatus'' X ''C. pecosensis'' hybrids quickly became widespread, occupying an estimated 50% of the native Pecos pupfish range by 1985. The widespread success of hybrids, and quick range expansion throughout native Pecos pupfish waters, has been hypothesized to be the result of selection mechanisms for hybrids during a period when the native ''C. pecosensis'' population had experienced a reduction. Additionally, hybrid populations have been reported to have increased growth-rates and vigor ( Heterosis), resulting in Pecos pupfish females to actively choose to mate with hybrids over pure male Pecos pupfish. Given this, conservation efforts have been difficult and efforts are being made to prevent ''C. variegatus'' from entering into isolated ''C. pecosensis'' populations.

References

Cyprinodon Endemic fauna of the United States Fish of the Western United States Freshwater fish of the United States Endemic fauna of Texas Natural history of New Mexico Pecos River Taxa named by Anthony A. Echelle Taxa named by Alice Fitch Echelle Fish described in 1978 Taxonomy articles created by Polbot {{Cyprinodontiformes-stub