Brown tang, Twotone tang, Scopas tang, Brush-tail tang
Zebrasoma scopas, the brown tang, twotone tang, scopas tang or brush-tail tang, is a species of marine ray-finned fish belonging to the family Acanthuridae which includes the surgeonfishes, unicornfishes and tangs. The brown tang is found throughout Oceania and is a herbivorous fish, feeding predominantly on filamentous algae. It is a highly popular fish in the aquarium trade.
Zebrasoma scopas has the specific name scopas, meaning “broom”, a reference to the bristles on the caudal peduncle near the spine.
Zebrasoma scopas is a laterally compressed, deep bodied fish with a protruding snout which grows to a maximum published standard length of 40 centimetres (16 in). The head is whitish and the body pale brown shading to a dark brownish-black near the black tail. There are faint pale green longitudinal lines starting as dots at the head end and becoming continuous and then dotted again posteriorly. The juveniles are rather paler and have yellowish bars near the anterior end. They also have relatively larger dorsal fins. The adults have a white spine on the caudal peduncle. The large, sail-like dorsal fin has 4 or 5 spines and 23 to 25 soft rays. The anal fin has 3 spines and 19 to 21 soft rays.
Zebrasoma scopas is found in the Indo-Pacific region, living at water depths of up to 60 metres (200 ft). Its range extends from the coasts of East Africa to Japan, the Pitcairn Islands, Malaysia, Indonesia, Japan, Australia, Lord Howe Island and Rapa Iti. In 2008, a brown tang was observed near Fort Lauderdale, Florida, far outside its native range.
Zebrasoma scopas feeds mainly on filamentous algae. For this purpose it has specialised pharyngeal teeth. It is usually found on the exposed side of reefs and in coral-rich lagoons. The adults are gregarious and sometimes form schools but the juveniles are solitary and are often to be found swimming among corals.
The brown tang is monogamous, though spawning has been observed both between pairs and among small groups. The male tends to be larger than the female. The fish rush up to the surface to spawn, fertilisation is external and the eggs are scattered in the water column. The larvae are planktonic for several weeks before settling and undergoing metamorphosis into juveniles.
