Western Pacific: southern Korea, southern Japan, ?Ogasawara Islands, Taiwan, southern China, Malaysia, Singapore, Thailand, Andaman Islands, Indonesia, Philippines, Yap, Palau, Pohnpei (Caroline Islands), Solomon Islands, Papua New Guinea, Vanuatu, New Caledonia, and Australia. Often misidentified as Siganus canaliculatus.

Body olive green or brown above, silvery below; fish frequently with a dark patch below origin of lateral line. Adults become mottled when frightened. Slender, pungent, venomous spines. Preopercular angle 89°-95°. Lower half to 2/3 of cheeks commonly covered with weak, scattered scales. Midline of thorax between pelvic ridges. Differs from S. argenteus in details of coloration and less deeply forked tail.

Inhabits algal and seagrass flats and shallow lagoon and coastal reefs. Forms schools. Mainly diurnal. Juveniles feed on filamentous algae, adults feed on leafy algae and seagrasses