Axolotls, Ambystoma mexicanum, are also known as Mexican Walking Fish, but they not fish at all.
Axolotls are, in fact Amphibians, part of the salamander family - and are in the same class as frogs & toads.
It is often misunderstood that salamanders (including axolotls) are lizards or reptiles. This is incorrect, as salamanders, being amphibians are entirely different animal, even though they may look similar.
Coming from the old Aztec word "Nahuatl", the name "Axolotl" is obtained from the Aztec god Xolotl, who was believed to be the god of death and bad luck. Furthermore, the name Xolotl may also be translated as "water-dog" and in my opinion I can not see this adorable amphibian having anything to do with the myth of Xolotl, not to mention death. But hey...the myth behind this delightful little creature doesn't affect them and that is all that matters!
The Axolotl originated from both Lake Xochimilco and Lake Chalco, in the Valley of Mexico. Sadly, Lake Chalco has been drained, in an effort to prevent flooding, and for expansion. The only remains of Lake Xochimilco are canals. Due to this, axolotls are now extremely endangered in the wild. :(
Amazingly, Axolotls are able to 'regenerate' any lost limbs. Losing an arm is no problem - just grow another one! The younger the axie is, the better the chance of the limb to grow back perfectly. Of coarse, there is always the worry of an open wound getting infected, but hey - it is SO COOL! I wish I could do that.. ;P
Most salamander larvae are very much like axolotls before metamorphosing into terrestrial creatures - only returning to water to breed. Although, unlike most salamanders, axolotls do not metamorphose, but keep their gills and cute little state, they do not grow the protruding eyes, eyelids or any of the other salamander characteristics. This is called neoteny. Axolotls are one of the few completely aquatic salamanders, they are truly special. :)
They can, however, gulp water from the surface if there is not enough oxygen in the water.
There are, some cases of axolotls metamorphosing into terrestrial creatures, but only when the 'right' hormones are added. This isn't natural at all, and is extremely stressful for the poor axie, decreasing their life span dramatically. Most die during the process. Please, don't try this, you will just end up killing your pet.
BUT, with the right care and love, axolotls live for an average of 10-15 years. About the same length as a dog! :D