u have cat then fish ,can anybody explain how they got catfish?

Animal nomenclature is flawed on a multitude of levels. We named things long before developing a taxonomy for them, so all sorts of animals have weird names or misnomers. The electric eel isn't an eel, the mountain lion isn't a lion, and there's the bearcat which is neither related to bears or cats.

I guess someone saw whiskers and decided it was reminiscent of a cat