Devils Hole pupfish

What it is

The Devils Hole pupfish lives only in Devils Hole, a water-filled limestone cavern in a detached unit of Death Valley National Park, inside Ash Meadows National Wildlife Refuge, Nevada. IUCN lists it as Critically Endangered. Almost the entire wild life cycle happens on a shelf of about 215 square feet. Spring counts have swung from a 25-year high of 191 in 2024 to 38 after earthquake seiches in spring 2025, then 77 in spring 2026. A captive refuge population is held at the Ash Meadows Fish Conservation Facility.

Range

One hole in the Mojave Desert. Nowhere else.

What happened

Groundwater pumping once threatened the water level (Cappaert v. United States, 1976). Earthquakes, thin algae, and a gene pool of dozens keep the count violent. In 2025 managers released captive-bred fish into the hole for the first time. “Dozens in one spring” is the honest long-run picture, even when a good year hits the low hundreds.

When / status

Critically Endangered now. One spring, a fluctuating handful.

Human role

Aquifer pumping was the historic threat; the species now survives as a managed relic.

Sources

IUCN Red List (Cyprinodon diabolis, CR); NPS spring 2025 count; USFWS 2026 update (77).