the.com/mud puppy

means A large aquatic salamander (genus Necturus) that retains its feathery external gills and stays in the water its whole life, never undergoing full metamorphosis into a land-dwelling adult.

from The name is plain old folk-naming, not deep etymology: 'mud' for the murky riverbeds and pond bottoms where it lives and hides, and 'puppy' because early observers thought its squeaky vocalizations and whiskery-looking external gills gave it a dog-like look and bark. There's no real canine connection — it's a nickname born from muddy water and a bit of human imagination, not biology.