My turtle wont eat live food?

he is a baby Mississippi map turtle i have a couple of feeder fish a snails in the tank instead of eating them he made friends with them. no wen i feed my turtle pellets the fishes actually go in his mouth trying to get his food and he doesn't do anything about it. should i but exotic fish to make it a tropical/ turtle tank or is there a way he will eat the fishes and the snails? he is the size of 4 quarters about 7 months maybe less