Is there a Fish-Fish no mi?

Question

Is there any Zoan Akuma No Mi that gives the user the ability to transform in fish (Fish-Fish No Mi)? If so can the user swim in the sea?

@Edit: I don't read the manga, so I don't know if anything like this has already happened or not

Answer 1

We have not yet seen a Fish Devil Fruit user. They will not be able to swim underwater due to the Devil Fruit curse, but they will be able to breath underwater due to the Fish's abilities.

Seeing as there has not been a Fish Fruit user thusfar, this statement is speculated on the very similar case that we have seen, where a fishman had eaten a devil fruit. Vander Decken IX, a Japanese bullhead shark fishman, ate the Mark Fruit. In chapter 615, Vander Decken IX explains that due to the Devil Fruit Curse, he is rendered unable to swim. We can later see him in chapter 631, where he has put an air-bubble around himself to retain his energy and not to make him able to breathe. This last part is confirmed at the end of the arc, because even after the air bubble had been removed from Noah, Vander Decken IX did not suffocate and was seen alive, being arrested, instead of buried.

Answer 2

To answer your question: Currently there is no fruit known as Fish Fish no mi, or similar in effect as you describe.

There has, however, been a question pretty similar to this before (Would a water manipulating Devil Fruit user be able to swim?) which will provide a bit more insight in this, although it is still speculative.

Answer 3

Based on a leak for chapter 999,

Kaido has one.