Catarina pupfish
A tiny Mexican spring fish that vanished in 2014.
The Catarina pupfish was a small species found only in one spring in Nuevo León, Mexico. Captive breeding failed to save it, and the last individual died in 2014.
- Reached only four centimetres in length.
- Lacked pelvic fins and pelvic girdle completely.
- Found in just one spring in Nuevo León, Mexico.
- Last individual died in 2014 in California.
- First fish discovered with autosome/Y chromosome fusion.
What it is
The Catarina pupfish was a very small freshwater fish belonging to the family Cyprinodontidae. Adults reached a maximum length of four centimetres. Males displayed iridescent blue colouring on their nape and sides, along with a dark patch near the tail base. Females appeared golden olive with a faint side band. A key physical trait was the complete absence of pelvic fins and the pelvic girdle. This miniaturized form made it one of the smallest fish recorded in North America.
Where it lives
This species existed solely in a single spring located in southwestern Nuevo León, Mexico. It shared this limited habitat with the Potosi pupfish. The population relied entirely on this specific freshwater source. When the main spring dried out in 1994, wild numbers collapsed rapidly. No other natural populations were ever documented outside this single location.
How it lives
Males did not establish breeding territories like many related species. Instead, they used jaw-nudging during courtship displays. Aggressive interactions involved flaring the operculum. These behaviours likely evolved due to competition with the larger Potosi pupfish. The smaller species was restricted to shallow, vegetated areas where it could avoid dominance by its cohabitant. Miniaturization and fin loss may have resulted from these environmental pressures.
Breeding and life cycle
Reproduction involved unique male courtship rituals distinct from other North American cyprinodontids. The species lacked male territorial defence of spawning sites. Captive attempts to maintain breeding colonies failed repeatedly. In the final surviving group, the last female died in 2013 after producing only male offspring. Hybridization efforts with the Potosi pupfish produced females, but backcross individuals did not survive long-term.
Fish and people
Conservationists attempted to save the fish through captive breeding programmes starting in the late 1980s. Facilities in Mexico, Europe, and the United States tried to keep colonies alive. All efforts ultimately failed as the fish proved difficult to maintain in captivity. The last known individual died in a laboratory in Berkeley in 2014. The extinction highlights broader risks facing Mexican freshwater fauna, with many species threatened by habitat loss and overexploitation.
Status and threats
The Catarina pupfish is officially extinct. It disappeared from the wild in 1994 following habitat drying. Captive populations persisted until 2014 but could not be sustained. The species is listed as extinct on the IUCN Red List. Its demise reflects wider conservation challenges in Mexico, where numerous endemic fish face threats from dewatering, pollution, and invasive species. Approximately forty percent of described Mexican freshwater fishes are currently considered at risk.
Questions people ask about Catarina pupfish
Why did the Catarina pupfish go extinct?
The wild population vanished in 1994 when its single spring habitat dried up. Captive breeding attempts in multiple countries failed to sustain the species, leading to the death of the last individual in 2014.
What makes the Catarina pupfish unique biologically?
It lacks pelvic fins and girdles entirely. Males also possess fewer chromosomes than females due to a rare genetic fusion event, a first discovery in fish taxonomy.
Where was the Catarina pupfish originally found?
It was endemic to a single spring in southwestern Nuevo León, Mexico. It shared this habitat exclusively with the Potosi pupfish before disappearing from the wild.
Was any part of the species saved in captivity?
No. Despite efforts in the US, Europe, and Mexico, all captive colonies perished. The last male died in 2014, confirming total extinction of the species.
Good reading and sources
The facts on this page come from the Wikipedia article "Catarina 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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