Devils Hole pupfish populations more than doubled over the past year, reaching 137 fish during an October survey conducted by the National Park Service, the Water Education Foundation reported.
Biologists counted 137 of the rare blue fish on Oct. 10, 2026. That total marks a sharp increase from the 77 fish recorded during the spring 2026 survey. It also more than doubles the 69 fish observed in the fall of 2025.
The entire wild population of the tiny fish lives on a shallow limestone shelf inside a water-filled sinkhole. This habitat sits within the Ash Meadows National Wildlife Refuge in Nevada. For years, the species has struggled to maintain a population above 100 individuals.
Pupfish Became Endangered as Groundwater Pumping Lowered Water Levels
Federal regulators listed the Devils Hole pupfish as endangered in 1967. The listing came under the Endangered Species Preservation Act, which preceded the current Endangered Species Act passed in 1973.
Populations began a steep decline during the 1990s. Increased groundwater pumping in the surrounding region drove that drop by lowering water levels inside the subterranean habitat.
Pupfish Count Details
| Survey Period | Fish Count | Comparison |
|---|---|---|
| Fall 2025 | 69 | Baseline |
| Spring 2026 | 77 | Up from baseline |
| Fall 2026 | 137 | Up from spring |
Wildlife biologists continue to monitor the limestone shelf twice a year. The National Park Service survey on Oct. 10, 2026, captured the highest autumn count in years.
Questions About Devils Hole Pupfish Habitat and Decline
Where do Devils Hole pupfish live?
Every wild Devils Hole pupfish lives on a single shallow limestone shelf inside a subterranean sinkhole. This unique habitat is located within Nevada’s Ash Meadows National Wildlife Refuge.
Why did the population decline in the 1990s?
Populations dropped significantly following growing regional groundwater pumping. That extraction lowered the water level over the shallow limestone shelf where the fish feed and spawn.
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