Fish and fishes are both accepted plurals, but they often point to different meanings.
Fish is the most common plural in everyday English. It usually means more than one fish of the same kind, or it can function as a collective noun when you are talking generally about fish as food or as animals.
- Same kind: “We saw three fish near the dock.”
- General sense: “Fish live in many different habitats.”
Fishes is typically used when you want to highlight different species or types. You will see it more often in biology, conservation, museum labels, and nature writing, where the distinction matters.
- Multiple species: “The reef is home to many fishes, including clownfish and surgeonfish.”
- Scientific tone: “Freshwater fishes vary widely across regions.”
In casual conversation, fish will almost always sound natural. Choose fishes when you are specifically counting or emphasizing variety across species. If you mean “many individuals of one kind,” fish is the safer default.