Axolotl

The axolotl is a neotenic salamander, also called the Mexican walking fish. However, it is an amphibian and not a fish. Initially, the amphibian was in lakes around Mexico City, like Lake Xochimilco. They possess similar features like salamander larvae, including a caudal fin and external gills. 

Their heads are broad, with lidless eyes, long, thin digits, and underdeveloped limbs. The females have noticeably more full bodies while the males spot swollen cloacae (posterior opening) lined with papillae. When injected with salamander hormones, the axolotl resembles a typical salamander. Scientists also like the amphibian because of its regenerative abilities. The ability to grow back its limbs hasn’t prevented the population from becoming gravely endangered.