Which amphibian is known as the 'Mexican walking fish'?

The amphibian known as the “Mexican walking fish” is the axolotl. Despite its nickname, an axolotl is not a fish but a salamander: the species Ambystoma mexicanum, a member of the mole-salamander family.

The name refers to its original home in the lakes and canals of the Valley of Mexico, especially Lake Xochimilco near Mexico City. Axolotls are famous for neoteny, meaning they reach sexual maturity while retaining larval features such as external feathery gills and a fully aquatic lifestyle. Unlike most salamanders, they usually do not transform into a land-dwelling adult.

The nickname can cause several mix-ups. Axolotls are related to tiger salamanders, and other aquatic salamanders—including mudpuppies—may also look vaguely fish-like. However, “Mexican walking fish” is the established common nickname for the axolotl. Their four legs allow them to walk along the bottom, while their regenerative abilities have made them important laboratory animals.

Wild axolotls are critically endangered. Habitat loss, pollution, and introduced fish have severely reduced their natural population, although captive axolotls are widespread in aquariums and research facilities.