The axolotl , also known as the Mexican walking fish, is a neotenic salamander related to the tiger salamander. Although colloquially known as a "walking fish", the axolotl is not a fish but an amphibian. The species was originally found in several lakes, such as Lake Xochimilco underlying Mexico City. Axolotls are unusual among amphibians in that they reach adulthood without undergoing metamorphosis. Instead of taking to the land, adults remain aquatic and gilled.