This is an Axolotl (Mexican walking fish). They are endemic and live only in the still rivers of Mexico city. They are endangered due to pollution and loss of habitat. They are a member of the salamander family and are unique because they can regrow missing limbs. They breathe with their external gills; some their whole lives. Others for no known scientific reason shed their gills and then walk on land. They can be kept as pets in an aquarium if they are bred sustainably.