Our snorkel guide was a marine biology student and he seemed super knowledgeable as well as passionate about the reef. Took a ton of precautions before going out on reef.
The question about feeding the fish bananas actually did come up. His response was look around you. We snorkeled the reef about 1/4 mile off El Mujeras Island. If that. He quickly pointed out that banana trees as well as jackfruit trees and many other fruit trees where growing all along the coast and the fish naturally eat them as part of diet.
So idk.
I would be more worried to see one with a margarita in its hand and highly suspicious what it was doing to its liver in that case