None of those snakes should be eating fish.
Snakes aren't people and they don't need snacks. Attempts to treat snakes like people instead of snakes can only result in incorrect husbandry. Now, I'm not at all one to say that snakes should be kept a particular way, but I don't think there's any logical basis for giving snakes snacks. If you want to give a pet a treat, give it to your dog, not your snake.
