The Parrotfish

Parrotfish are mostly tropical, perciform marine fish of the family Scaridae. Abundant on shallow reefs of the Red Sea, Atlantic, Indian and Pacific Oceans, the parrotfish family contains ten genera and about 90 species.
Parrot fish are named for their dentition; their numerous teeth are arranged in a tightly packed mosaic on the external surface of the jaw bones, forming a parrot-like beak which is used to rasp algae from coral and other rocky substrates (a process called bioerosion). Many species are also brightly coloured in shades of blue, green, red and yellow, but are not especially popular as pets.
Although they are considered to be herbivores, parrot fish eat a wide variety of organisms that live on coral reefs. Some species, for example Bolbometopon muricatum may include corals (polyps) in their diet. Their feeding activity is important for the production and distribution of coral sands in the reef biome and can prevent algae from choking coral. The teeth grow continuously, making it hard to curb overgrowth in the aquarium. Ingested during feeding, coral rock is ground up by the pharyngeal teeth. After they digest this it is excreted as sand thus at times creating small islands and the idyllic sandy beaches of the Bahamas and Caribbean.

Parrotfish - Sparisoma cretense
Ovoid, elongated and slightly compressed body. Terminal mouth with strong jaws and beak-like teeth. Female fish are reddish and males brownish or greenish. Found on rocky bottoms and close to Neptune grass, from 3-4 metres to 40-50 metres. Maximum size 50 centimetres.

Male Parrotfish

At the wreck

Female Parrotfish