Fishmen And Their Queen, The (1995)

aka: La Regina Degli Uomini Pesce

Set in a post-apocalyptic world, two young boys (Giuliano Gensini and Michael Velez) attempt to escape to a mysterious island rumored to be untouched by the ravages of destruction. However, after finding the island, the two boys discover it to be ruled by a merciless queen (Ramona Badescu) who changes men into fish. Enslaved by the queen, these Fishmen are forced to seek the mythical treasure of Atlantis. But the arrival of the two boys sparks the fire of revolt among the Fishmen against their Queen.