Stoplight Parrotfish

The Stoplight parrotfish is a sex-changing fish inhabiting coral reefs in Florida, Bahamas, the Caribbean, eastern Gulf of Mexico, Bermuda, and Brazil. Its typical length is between 30 and 45 cm, but it can reach 60 cm at times. It is normally found during the day between 0,5 and 16 meters[1]. The colors of the Stoplight parrotfish in the initial phase, when it could be either a male or a female, are dramatically different from those in the terminal phase, when it's definitely a male.

The common name, stoplight, comes from the marked yellow spot near the pectoral fin, which is clearly visible only in specimens in the terminal phase.

Parrotfish are named for their dentition, which also is distinct from that of other Labrids. Their numerous teeth are arranged in a tightly packed mosaic on the external surface of the jaw bones, forming a parrot-like beak with which they rasp algae from coral and other rocky substrates[4] (which contributes to the process of bioerosion). Although they are considered to be herbivores, parrotfish eat a wide variety of reef organisms, and it is important to note that they are not necessarily vegetarian. Species such as green humphead parrotfish (Bolbometopon muricatum) include coral (polyps) in their diet.[4] 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, replacing material worn away by feeding.[5] The pharyngeal teeth grind up coral rock that the fish ingests during feeding. After they digest they excrete the rock as sand helping to create small islands and the sandy beaches of the Caribbean. One parrotfish can produce 90 kg of sand each year.[6] Maximum sizes do not vary widely within the family, with the majority of species reaching 30–50 centimetres (12–20 in) in length. However, a very few species reach almost 1 metre (3.3 ft), and the green humphead parrotfish reaches up to 1.3 metres (4.3 ft).[7] Their bodies are deep, with large, thick cycloid scales, large pectoral fins and homocercal tail fins. Parrotfish use their pectorals as their primary means of locomotion, engaging the tail only to achieve higher speed.