ok first off all salamander larvae and mudpuupies are called water dogs. so lets ditch that name. if it is a mudpuppy, its gonna get 18 inches and be aquatic for its life. if its a pacific giant, tiger, or spotted salamander larvae then it will be aquatic for about 3-6 months then turn terrestrial for the rest of their life. they will eat shrimp and small fish. also clams and de shelled snails, along with aquatic frog pellets and newt pellets.if it is a mudpuppy then they will eat all of thoose things and will relish crawfish. they need about 12 inches of water if they are a salamander larvae, and any amount of water over 18 inches for a mudpuppy. also they need a tank of at least 10 gallons(larvae) and 75 gallons (mudpuppy) hope this helps