Chlorurus microrhinos also known as Steephead Parrotfish occurs in tropical marine waters of the Western and Central Pacific.
The Steephead Parrotfish has large exposed tooth plates. The upper plate has one or two canines on each side. The head profile becomes very steep in adults. The caudal fin is rounded in juveniles but changes to truncate with elongate upper and lower lobes in adults.
Both sexes are usually green-blue overall with a pinkish bar on each scale. The tooth plates are blue-green. There is a blue-green band above the mouth and a wider one below. An irregular blue-green line crosses the cheek, below which the head is usually greenish-yellow. This species also has a less common red phase. Uniform yellowish-tan individuals are known but are rare. Steephead Parrotfish juveniles below about 8 cm are black with horizontal white stripes. Juveniles are generally solitary and large adults often school together. Chlorurus microrhinos grows to 70 cm in length, quite aside that he only eats corals, this fish is not suitable for our aquariums
By the way, the picture show a sleeping Steephead Parrotfish (Chlorurus microrhinos) in nighttime colouration.