Axolotls are really interesting animals. They are not mud puppies, but are axolotls. What makes them so interesting is that they exhibit neoteny - which means that the adult that you see is actually a larval form that has not developed into a true adult. In the laboratory you can grow them in excess thyroid hormone, and they will undergo metamorphosis (much like a tadpole does), and form an organism that never actually appears in the wild. There are numerous web sites about them, and their color and genetics have been extensively studied, probably more than any of our captive marine fish. I think that they would make very interesting pets.