The Pupfish, genus Cyprinodon, is a tiny fish that lives in springs, ponds, marshes, and slow-flowing streams in the deserts of southwestern North America. Pupfish are found in the Mojave and Sonoran Deserts (in northwestern Mexico, southern California, USA, and Arizona, USA).

Many types of pupfish are endangered species due to a loss of habitat and to competition from exotic species of fish that have been introduced to their habitat.

Lifecycle: Towards the end of summer, most desert pools and other desert waters dry up, killing most pupfish. Only a few bodies of water do not dry up completely, so very few pupfish survive. During the coldest parts of winter, pupfish burrow into the muddy bottom and become dormant until the weather warms up. They then mate and reproduce quickly. Most pupfish have a life span of less than one year.

Diet: Pupfish eat diatoms (microscopic unicellular algae with a hard cell wall), algae, and small aquatic invertebrates (like amphipods, gastropods, and ostracods).

Some pupfish engage in "pit digging," in which the fish rests at the water's bottom and wiggles its body in order to to churn up the mud and sand. No one is sure exactly why they do this, but it may be to dislodge food from the mud.

Anatomy: The Pupfish is a tiny fish, about 2 to 2 1/2 inches (5-6.5 cm) long. Pupfish range in color from silvery-brown to silvery-blue.