it swims?
Verb
a gold fish swims in a fish tank or the sea.It Swims I The Water And Eats Fish Food
The word like can be a verb, or a conjunction (meaning as, similar to), and more rarely a noun.It is arguably acting as a preposition in constructions such as "swims like a fish" (truncated clause like a fish swims).
If it looks like a fish, swims like a fish, smells like a fish, has horns like a fish, has legs like a fish and eats grapefruit like a fish--most likely it's a fish.
because it swims
"A polar bear can swim like a fish," or "A polar bear swims like a dog: it always uses the doggie paddle when in the water."
A barracuda is a fish and like other fish it uses gills to extra oxygen from the water in which it swims.
it looks tried and swims slow and stay on the bottom
An eel swims but looks like a snake.
goldfish
Shark fish