Sergeant majors are a type of damselfish and are very territorial. Males fiercely guard their nests of purplish eggs from large fish and divers. In the wild, sergeant majors can also act as cleaners to other fish and turtles, feeding on annoying parasites. Many of the aquarium divers fear the sergeant major above all other fishes, even the sharks. Why? Because the males attack the divers while they are doing their routine maintenance when they approach a nest. Divers are required to wear hoods and gloves to protect themselves from small bites from these aggressive fish.