Pupfish is any of about 30 species of small fish that live mainly in springs and streams in the southwestern United States and Mexico. Pupfish have inhabited these waters for at least 50,000 years, before the end of the most recent ice age. At that time, rivers and lakes covered the area, much of which is now desert. Isolated groups of pupfish survived after most of the water had dried up. One species, the Devils Hole pupfish, has lived over 20,000 years in a deep spring in Nye County, Nevada. This area is now in Death Valley National Park.
Several species of pupfish have become extinct, and other species are endangered. In the 1970’s, scientists and conservationists began working to protect the surviving species. The Devils Hole pupfish has been legally protected since 1976. The population of this species has been reduced to only about 200 individuals at times.
Pupfish can live in water where few plants and animals can survive. Some pupfish normally withstand water temperatures up to 108 °F (42 °C). Pupfish have an average length of about 11/2 inches (3.8 centimeters). The females and young are olive brown and white, with black bars on their sides. The males are blue and purple, with black bars and dark-edged fins.
