Is fishes a plural of fish?

No, "fishes" is not the plural of "fish".

Here's the breakdown:

* Fish can be both singular and plural.

* Singular: "There's a fish in the tank."

* Plural: "There are many fish in the ocean."

* Fishes is used when referring to different kinds or species of fish.

* "The aquarium has a variety of fishes, including goldfish, angelfish, and sharks."

So, in most cases, "fish" will be the correct plural form. "Fishes" is a more specific term used when discussing different types of fish.