Scarus chameleon

Lore & Background

Until 1986, Scarus chameleon was misidentified as Scarus lunula, a synonym of Scarus festivus. It is similar in appearance to S. festivus, which is its closest relative and overlaps with it in distribution. The type locality is Sumilon Island in the Philippines.

The species is known to reach 248 mm SL. Females may be sexually mature by the time they reach 115 mm SL. Females may be as small as 149.5 mm SL before transitioning into terminal phase males, but females as large as 175.5 mm SL are known. Like most parrotfish, S. chameleon changes colour phase as it grows.

The young juveniles, initial phase, and terminal phases are all highly variable in colouration and able to rapidly change colouration, which is a challenge when attempting to identify it. The initial phase includes females and primary males, and may appear very similar to northern and inshore populations of the closely related and more common S. rivulatus. The secondary males of the terminal phase are more distinct, but such terminal phase fish can change rapidly colours between light and dark coloured liveries.

Reader's Guide

Scarus chameleon is notable primarily for its remarkable ability to rapidly change colouration, which is the basis of its common name. This trait is present across all life phases—juveniles, initial phase, and terminal phase—making identification challenging. The species was historically misidentified as Scarus lunula until 1986, reflecting the taxonomic confusion caused by its variable appearance. Its closest relative is Scarus festivus, with overlapping distributions.

The initial phase, including females and primary males, can closely resemble northern and inshore populations of the more common Scarus rivulatus, further complicating field identification. Terminal phase males are more distinct but still capable of rapid shifts between light and dark liveries. The species reaches a maximum recorded length of 248 mm, with females reaching sexual maturity at 115 mm and transitioning to terminal phase males at sizes ranging from 149.5 mm to 175.5 mm. Its distribution across Pacific and eastern Indian Ocean reefs underscores its ecological role in these habitats.