Waterdog

A "waterdog" is a larval (gilled, aquatic) tiger salamander, often sold as bait or mistaken for an axolotl — but unlike an axolotl it will eventually metamorphose and leave the water.

If a cheap "axolotl" starts losing its gills, growing eyelids, and trying to climb out, it is likely a waterdog that is maturing into a land salamander. The care then shifts to a terrestrial setup.