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.
An eel swims but looks like a snake.
it looks tried and swims slow and stay on the bottom
goldfish
Shark fish