June 19th, 2024
Creature Feature: Desert Pupfish
Author: Rachel Noriega
You don’t hear the words fish and desert paired often, but don’t tell that to the desert pupfish (Cyprinodon macularis). These fish are around two inches long, round bodied, and olive-colored with dark vertical barring. Desert pupfish have a limited range and can only be found in the Salton Sink Basin of California, the Laguna Salada Basin, and the Colorado River Delta in Mexico.
As you might expect, water in the desert provides extreme environmental conditions and desert pupfish are up to the task. Though these are freshwater fish, they have to tolerate salinity ranges of 68-70 parts per thousand (ppt)—for reference ocean water averages 35ppt. Desert pupfish can also tolerate oxygen levels as low as 0.1 part per million and water temperatures as high as 108 degrees Fahrenheit. To survive—and avoid—rapid changes in salinity and temperature conditions, desert pupfish can dive into the substrate. With all these unique abilities, you might think the desert pupfish would be invincible, but the desert pupfish is an endangered species.
Desert pupfish are endangered because of habitat destruction and alteration combined with the introduction of non-native species. Their habitats face encroachment by tamarisk (Tamarix spp.), unreliable water supplies, excessive vegetation, and vandalism. Non-native species like mosquito fish, carp, and sailfin molly (Poecilia latipinna) pose a threat to pupfish through predation, competition, and disease. Extreme water conditions can help pupfish, since these conditions control non-native populations are not adapted to these stressors.
California Department of Fish and Wildlife is working with various agencies, governments, and private entities to conserve the desert . These conservation efforts include monitoring populations, restoring target habitats, controlling non-native species populations, and salvaging pupfish from areas that are being dewatered.
Bonus fact: During the breeding season (summer) male pupfish turn blue with yellow fins!
Desert Pupfish – Great Ecology
