You have always been able to fish in minecraft, but all you would do is throw a bobber into water that has never once had a fish in it. Adding fish in minecraft would make it so you could SEE the fish in the water. When a bobber would near the fish, you would see it nibble on the line until it bites! There could be a small, medium/average, large fish you could catch, and each would give you different amounts of hunger back! This would add no only a much better way to fish and gather food in minecraft, but a cool feature visually as well!