Better Fish AI is absolutely necessary to have a complete game, you don't need anything else but Fish. If you dont have good fish AI, then your game is a solid 2 out of 10. No but seriously, in ocean planets, there should be tons of species of fish, rather than the usual 2 small fish and 0-2 big fish. And also, smaller fish should go around in schools of fish, if you go near it or into it, they all swim away and when you've left them they regroup. And maybe some sort of a food chain system, like some big fishes eat other big fishes, and those big fishes eat smaller fishes, but the schools of fish hang around the first big fishes for protection.