Masked Grouper

The maximum recorded total length is 45 centimetres (18 in). The masked grouper has an oblong, rather compressed body in which the standard length is 2.6 to 3.3 times its depth. The dorsal profile of the head is convex while the area between the eyes is slightly convex. The preopercle is rounded with fine serratations and with a smooth, fleshy lower margin. The gill cover has a central spine which is located at one-third of the gap between the lower to upper spines and with an upper edge which is distinctly convex The dorsal fin contains 9 spines and 14-16 soft rays while the anal fin has 3 spines and 9-10 soft rays. The membranes between the dorsal fin spines are incised in juveniles but not in adults. The caudal fin is truncate.

This species has a greenish to reddish-brown or brownish-grey body, with a large roughly square-shaped white blotch on the upper flanks and dark diagonal lines on its head. There are narrow dark bars along the middle of the flanks, and a white base to the caudal fin which has a black spot in the centre. The juveniles are colourful being violet with bright red margins on their dorsal, anal and caudal fins.

Gracila albomarginata can be found in the Indo-Pacific, from northern Mozambique north to Kenya east to French Polynesia and the northern Great Barrier Reef. Its range includes the islands of Réunion, Mauritius, Seychelles and the Maldives but it has not been recorded in the Red Sea or Persian Gulf. In Australia it is found at Scott Reef and Rowley Shoals in Western Australia, as well as the Great Barrier Reef in Queensland. It also occurs around Christmas Island and the Cocos (Keeling) Islands.