Cyprinodon nevadensis is a species of pupfish in the genus Cyprinodon. The species is also known as the Amargosa pupfish, but that name may also refer to one subspecies, Cyprinodon nevadensis amargosae. All six subspecies are or were endemic to very isolated locations in the Mojave Desert of California and Nevada. Specifically, the pupfish have been found in Tecopa Bore, Inyo County, which links to the Amargosa River and Saratoga Springs, in addition to the lakes connected to it.

Amargosa pupfish habitats in freshwater types, including streams, springs, and spring-fed ponds and lakes.

They are small in size, and usually grow up to 25-30 mm in several months, but rarely exceed 50 mm. These pupfish have deeper, broader bodies, with a blunt head and a small, oblique terminal mouth.

Amargosa pupfish are omnivores, and have a diet consisting of algae and cyanobacteria. They also eat small invertebrates.

Male pupfish are bright blue and have a black band on the edge of the tail fin. Female pupfish are olive-brown with metallic blue on their shoulders and upper sides during breeding stages. Male pupfish are protective of their breeding territories and aggressively drive off other male fish. Female disperse their eggs a few at a time and in different locations. Male pupfish guard the territory that the eggs are laid in.

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