The Rainbow Parrotfish is the largest in the Parrotfish family; it can grow up to 4 feet in size. In fact, it is the largest herbivorous fish in the Atlantic. Parrotfishes get their name from their teeth that are fused to form a strong parrot-like beak, which is used to scrape the algae off the surface of coral. Sadly the Rainbow Parrotfish is on the IUCN Red List of Threatened Species.