Some algae grazing fish, such as foxface or rabbitfish, can and will munch on zoanthids and other colonial polyp corals. This nipping can be unintentional, as the fish is merely trying to eat algae that is close by. However, there are a few tangs and rabbitfish that will actively eat coral polyps. This behavior is obviously not a desirable one in a reef tank, and chances are the fish won’t stop nibbling despite your best efforts. The only way to get the fish to stop is to remove it from your reef and relocate it to a fish only aquarium, or at least a reef tank that doesn’t have the type of coral the fish has developed a taste for.