A Rare Fish Found Underground in Death Valley Is Making a Comeback.
Divers counted 137 Devils Hole pupfish in a recent survey, nearly double the 77 found in spring, after conservationists added captive-raised fish and supplemental food to the Death Valley cavern.
The population of the Devils Hole pupfish, one of the rarest fish on Earth, has risen sharply, according to Yale Environment 360. Scuba divers counted 137 of the fish in the most recent survey, up from 77 in a survey conducted in the spring.
The fish are about two inches long and fluorescent blue. They are classified as endangered because they are highly vulnerable to disturbance. Their home is Devils Hole, a water-filled part of a limestone cavern more than 500 feet deep in Death Valley, California, a desert that is among the hottest places on Earth.
The report describes two main threats. Overpumping of groundwater at nearby farms has lowered water levels inside Devils Hole. Distant earthquakes also generate waves inside the cavern, which dislodge the algae the pupfish eat. Reverberations from earthquakes in 2024 and 2025 reduced the population to fewer than 40 individuals.
Conservationists responded in two ways. They introduced captive-raised fish to boost the ranks of the wild population, and they provided supplemental feed made of mysid shrimp, water fleas and blood worms. According to the report, those efforts are paying off.
Divers worked with researchers at the surface to tally the fish in both surveys. The spring count was 77. The latest survey, which the page says took place last month, found 137, nearly double the earlier total and well above the low point of fewer than 40.
The article also notes that it is not settled why a fish lives in the desert at all. Some researchers speculate that the pupfish were carried to the cavern by rivers and lakes that converged in Death Valley during a wet period. Others think birds or humans brought them there.
At a Glance
- Divers counted 137 Devils Hole pupfish in the latest survey, up from 77 in a spring survey.
- Earthquake reverberations in 2024 and 2025 cut the population to fewer than 40 individuals.
- Devils Hole is part of a limestone cavern more than 500 feet deep in Death Valley, California.
- Conservationists added captive-raised fish and feed made of mysid shrimp, water fleas and blood worms.
Sources
This brief was written by Brightside Report from the reporting linked above. Spot an error? Request a correction.