(Zanclus canescens), deep-bodied, tropical and subtropical reef fish, commonly placed alone in the family Zanclidae (order Perciformes). The Moorish idol is a striking-looking fish—thin, deeper than it is long, and with a protruding, beaklike mouth and a dorsal fin greatly extended in front. An Indo-Pacific fish, relatively common and found in shallow water, it is about 18 cm (7 inches) long and is boldly patterned with three vertical black stripes on a yellowish body.