The axolotl (/ˈæksəlɒtəl/; etymol. Nāhuatl āxōlōtl [aːˈʃoːloːt͡ɬ] (singular) or āxōlōmeh [aːˈʃoːloːmeʔ] (plural) "water monster"), also known as a Mexican salamander (Ambystoma mexicanum) or a Mexican walking fish, is a neotenic salamander, closely related to the tiger salamander. Although the axolotl is colloquially known as a "walking fish", it is not a fish, but an amphibian. The species originates from numerous lakes, such as Lake Xochimilco underlying Mexico City.