The small, heat-tolerant pupfish was endemic to the outflows of a pair of hot springs in the Mojave Desert of Inyo County, California.

Habitat modifications, the introduction of non-native species and hybridization with the related Amargosa River pupfish led to its extinction around 1979.

Most divergence of local Cyprinodon species likely took place during the early-to-mid Pleistocene, a time when pluvial lakes intermittently filled the now-desert region, though some may have occurred during the last 10,000 years.

The evaporation of the lakes resulted in the geographic isolation of small Cyprinodon populations in remnant wetlands and the speciation of C.

The resulting swifter currents caused downstream water temperatures to rise above a level to which the pupfish were adapted.

A population was found at a reservoir at a nearby motel two years later, but its smaller scales suggested that it may have already hybridized with the Amargosa River pupfish.

[9] In 1978, United States Fish and Wildlife Service announced that it was considering delisting the fish, with Assistant Secretary of the Interior Robert L. Herbst calling the loss "totally avoidable" and saying, "The human projects which so disrupted its habitat, if carefully planned, could have ensured its survival.