I want to know if the plural of fish is both fish and fishes
Both are used. Nowadays, the regular form, 'fishes' is more often used when discussing various species. Books, for instance, have titles such as Freshwater Fishes of Wisconsin and Peninsular Michigan, while 'I caught three fish last weekend' is a more common use of plural 'fish'.
Please read this thread for your answer.
Students: Are you brave enough to let our tutors analyse your pronunciation?
What is the correct plural of fish?
 Clive's reply was promoted to an answer.
Teachers: We supply a list of EFL job vacancies