pupfish

The term "pupfish" refers to certain killifishes, primarily those belonging to the genus Cyprinodon. These small fish, typically found in warm streams and springs in the western United States, are part of the family Cyprinodontidae.1

Killifish, in general, are a diverse group inhabiting waters worldwide, including brackish, salt, and fresh water, and even desert hot springs. Some killifish species have unique adaptations, such as burying their eggs in dry mud to survive annual droughts, with their life cycles often lasting only about a year. While some killifish are kept in aquariums or used as bait, others, like certain pupfish species, are listed as endangered. It's important to note that "puppyfish" is a separate term referring to monkfish.23