About Gracila albomarginata (Fowler & Bean, 1930)
This species, commonly called the masked grouper, has the scientific name Gracila albomarginata (Fowler & Bean, 1930). The masked grouper has an oblong, relatively compressed body, with a standard length that is 2.6 to 3.3 times its body depth. The dorsal profile of the head is convex, and the area between the eyes is slightly convex. The preopercle is rounded, with fine serrations and a smooth, fleshy lower margin. The gill cover has a central spine located one-third of the way across the gap between the lower and upper spines, and its upper edge is distinctly convex. The dorsal fin has 9 spines and 14 to 16 soft rays, while the anal fin has 3 spines and 9 to 10 soft rays. The membranes between the dorsal fin spines are incised in juvenile fish, but not in adults. The caudal fin is truncate. This species has a body colour ranging from greenish to reddish-brown or brownish-grey. It has a large, roughly square-shaped white blotch on its upper flanks, dark diagonal lines on its head, and narrow dark bars along the middle of the flanks. The base of its caudal fin is white, and there is a black spot at the centre of the caudal fin. Juveniles are more colourful, with violet bodies and bright red margins on their dorsal, anal, and caudal fins. The maximum recorded total length of this species is 45 centimetres, or 18 inches. Gracila albomarginata is distributed across the Indo-Pacific region, ranging from northern Mozambique north to Kenya, and east to French Polynesia and the northern Great Barrier Reef. Its known range includes the islands of Réunion, Mauritius, Seychelles, and the Maldives, but it has not been recorded in the Red Sea or the Persian Gulf. In Australia, it occurs at Scott Reef and Rowley Shoals in Western Australia, as well as the Great Barrier Reef in Queensland. It can also be found around Christmas Island and the Cocos (Keeling) Islands. The masked grouper is a reef-associated species, and it normally lives on the outer slopes of coral reefs and in channels near deep water. It feeds mainly on fish, which it catches near the seabed. This is an uncommon species that is usually solitary, though there are confirmed records of groups of three or four individuals.
