Desert pupfish
Small desert fish that survives extreme heat and salt
The desert pupfish is a small bony fish in the family Cyprinodontidae. It was first described in 1853 and is now listed as endangered in the United States.
- Survives water from 4 °C to 45 °C and salinities up to 70 ppt
- Males turn bright blue during breeding season
- Now found in only three drainage basins
- Listed as endangered in the United States
- First described in 1853 by Baird and Girard
What it is
The desert pupfish is a small fish, usually under 7.62 cm long. Males are larger and turn bright blue on the head and sides during breeding, with yellow or orange on the tail. Females and young are silvery or tan with narrow dark bars on the sides. The body is thick and flattened from side to side, with a rounded back and a mouth that sticks out slightly. It belongs to the family Cyprinodontidae.
Where it lives
It once lived in the lower Colorado River, the Gila, Santa Cruz, San Pedro and Salt rivers, and reached the Gulf of California. Today wild fish are found only in the Salton Sea basin in California and in parts of the Colorado River Delta and Laguna Salada basin in Mexico. Eleven natural populations remain in the two countries, with some reintroduced groups in Arizona.
How it lives
These pupfish live in shallow desert springs, streams and marshes. They feed on small animals and plants, especially chironomid midges and mosquito larvae, and they forage in the morning and evening. They can survive water from 4 °C to 45 °C, salinities up to 70 parts per thousand and very low oxygen. They avoid the midday heat by moving to deeper water.
Breeding and life cycle
Breeding takes place from early spring into winter when water is above 20 °C. Males hold small territories and court females that enter them. The pair forms an S-shape, the male wraps his anal fin around the female, and they jerk to release one egg. Larger females lay more eggs. The eggs are left in the substrate and hatch without further care.
Status and threats
The species is listed as endangered in the United States. Its decline began in the early 1900s because of habitat loss and the arrival of non-native fish such as tilapia that eat or displace it. Dams, water diversion and drying of springs have removed most of its former range. Eleven wild populations remain, and some fish have been moved to new sites in Arizona.
Questions people ask about Desert pupfish
How big is the desert pupfish?
Adults are usually less than 7.62 cm long, with males slightly larger than females.
Where does it live today?
Wild populations remain in the Salton Sea area of California and in parts of the Colorado River Delta in Mexico.
What makes it able to live in such harsh water?
It tolerates temperatures from 4 °C to 45 °C, salinities up to 70 parts per thousand and very low oxygen levels.
Why is it endangered?
Habitat loss from water projects and competition from introduced fish such as tilapia have removed most of its former range.
Good reading and sources
- Desert pupfish on WikipediaEncyclopedia
- More photos on Wikimedia CommonsPhotos
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Desert pupfish", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.
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