Cetoscarus bicolor

While this species is restricted to the Red Sea, there is a similar species which is widespread in the Indo-Pacific is Cetoscarus ocellatus, also sometimes called the bicolour parrotfish.[3][4] These species were formally classified as one, the only in the genus Cetoscarus, but there are major molecular and morphological differences between the two.[1] C. bicolor is associated with coral reefs. It usually can be found in lagoons and seaward reefs at depths between 1 and 30 m (3 ft 3 in and 98 ft 5 in).[3] Small juveniles are usually found among dense coral and in algae-rich habitats.[2]

It is among the largest parrotfishes, growing to a standard length of up to 50 cm (20 in).[2] As in many of its relatives, it is a sequential hermaphrodite, starting as female (known as the initial phase) and then changing to male (the terminal phase). The initial phase is dark brown with a large cream patch on the upper part of the body. The terminal phase is very colourful, overall green with pink spotting to the body and edging to the fins. Juveniles are white with a black spot on the dorsal fin and an orange band through the eye.

As in other parrotfish species, males are territorial. During its lifetime, this fish changes sex twice and very large females change sex to become brightly coloured males. This parrotfish mainly feeds on algae.[2]

• Photos of Cetoscarus bicolor on Sealife Collection