The plural of 'fish' is 'fish'. One fish. A hundred fish. It's the same as 'sheep' - the singular and plural forms are the same. Only two types of English-speaking people say 'fishes': 1. Scientists referring to different species. 2. Very small children who haven't learnt that you don't say 'fishes'. It sounds cute when a three-year-old says it. Less so with adults.

Fish is singular and plural. A lot of fish are called a school of fish. There are a lot of fish in the sea.

I never use the word fishes as the word fish even though it's correct. It just doesn't sound natural to me. For example: "I saw there are a lot of fish in the sea" or "look at all the fish" The only time I use fishes is a sentence like "he fishes a lot " You really only use "fishes" when you're talking bout the many species of fish. For example: "I own 6 fish" mean I can count 6 fish in my tank. They could be all one species like gold fish. "I own 6 fishes" that means I have 6 different types of fish like blue gill, gold fish, sword fish, tilapia, tuna, and cod for example.

"Fish" is the correct plural form. "Fishes" is incorrect in standard English.

The plural of fish is "fish" The reason you're confused is because people often use "fishes" to rhyme. It's not correct, but it rhymes. "If wishes were fishes, we’d all cast nets into the sea." And scientists who study fish use "fishes." I can explain if you want, but I would say... don't worry about it! Just know the plural of fish is "fish"