I read that in scientific contexts native speakers use "fishes." Is it used by scientists to refer to the same fish or different fish? Because if we are talking about a variety of fish it's not wrong to use "fishes."
If I am talking about my fish in the tank which would be grammatical and natural: "I have ten fish in my tank," I mean all are the same and "I have ten different fishes" meaning they are not the same.
It is generally accepted as correct to use "fishes" to mean "multiple types of fish".
Fishes of the World (title on a poster at my local fish and chip shop showing picture of many different types of fish)
It is non-standard (but quite common) to use "fishes" to mean multiple individual fish.
Because of this ambiguity, it is not common to say "There are three fishes". Instead you should say "There are three types of fish" (or species of... etc). But sometimes the context makes the meaning clear
It is quite common to use "fishes" to many "many fish of many species",
The fishes in the North sea have started to recover since quotas were introduced.
The primary purpose of this book is to provide for the identification of the 300 most common fishes that one might observe while snorkeling or diving on reefs of the Caribbean Sea
(in the latter, it should be obvious that there are more than 300 individual fish in the Caribbean sea)
If you say "I have 10 fish in my tank" I'd assume you mean ten individuals They might be all the same species, or they might be several different species.
If you say "I have 10 fishes in my tank" It might be understood to mean 10 individuals, or 10 species. It probably doesn't mean 10 that are the same.
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<>< <>< ()< ()< ()< [}< [}< = 7 fish, 3 fishes
