Tecopa pupfish
Extinct subspecies of killifish from California hot springs.
The Tecopa pupfish lived in the Mojave Desert before habitat changes and hybridization caused its extinction around 1979. It was the first animal removed from US endangered species protections due to its disappearance.
- Last seen in February 1970 near Tecopa, California.
- Survived water temperatures up to 43 degrees Celsius.
- First animal removed from US Endangered Species Act.
- Hybridized with Amargosa River pupfish after habitat changes.
- Measured only 2.5 to 4 centimetres in length.
What it is
This small fish belonged to the genus Cyprinodon within the killifish family. Adults measured between 2.5 and 4 centimetres. Males showed bright blue colours during breeding seasons, while females displayed vertical stripes. The dorsal fin sat near the tail, and pelvic fins were tiny or missing. They thrived in water reaching 43 degrees Celsius, a temperature most fish cannot survive.
Where it lives
The species existed only in the outflows of two hot springs near Tecopa in Inyo County, California. These waters flowed into the Amargosa River system. No other locations supported this specific subspecies. The springs sat at an elevation of 430 metres above sea level in the Mojave Desert region.
How it lives
They fed mainly on cyanobacteria, occasionally eating mosquito larvae. Their high heat tolerance allowed them to live in warm spring water. Other local pupfish species lived nearby in desert wetlands. The fish relied on isolated pools created by ancient pluvial lakes that evaporated over time.
Breeding and life cycle
Breeding males developed vivid blue colouration to attract mates. Females carried distinct vertical stripes along their bodies. Specific spawning timing and egg details are not recorded in available sources. Young fish grew within the warm spring environments.
Fish and people
Habitat destruction began when bathhouses were built in the mid-twentieth century. Spring pools were enlarged and channels diverted, raising downstream temperatures. Non-native species like bluegill entered the waters. The related Amargosa River pupfish migrated upstream and interbred with them. These factors led to the subspecies disappearing.
Status and threats
The last confirmed specimens were collected in February 1970. Surveys in 1972 and 1977 found no survivors. Officials declared it extinct in 1981 after extensive searches. It became the first animal removed from the Endangered Species Act because it no longer existed. Conservationists noted the loss was avoidable with better planning.
Questions people ask about Tecopa pupfish
Why did the Tecopa pupfish go extinct?
Habitat modification from bathhouse construction altered water flow and raised temperatures. Non-native species entered the springs, and the fish hybridized with the related Amargosa River pupfish, leading to its genetic disappearance.
Where did the Tecopa pupfish live?
It lived exclusively in the outflows of two hot springs near Tecopa in Inyo County, California. These springs fed into the Amargosa River system in the Mojave Desert.
What did the Tecopa pupfish eat?
Its primary food source was cyanobacteria, also known as blue-green algae. It occasionally consumed invertebrates such as mosquito larvae for additional nutrition.
Good reading and sources
- Tecopa pupfish on WikipediaEncyclopedia
- More photos on Wikimedia CommonsPhotos
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Tecopa 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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