Indo-West Pacific: Persian Gulf, Gulf of Oman, Pakistan, India, Sri Lanka, Burma, Thailand, Singapore, Malaysia, Indonesia, Papua New Guinea, Philippines, Cambodia, Viet Nam, south China, Taiwan and Western Australia. Also known from Ryukyu Islands; Palau and Yap in Micronesia.

Body silvery gray above, silvery below; a touch of olive green on nape and upper surface of head; fright pattern mottled with pale cream and dark brown; usually fish display a dark patch just below origin of lateral line. Preopercular angle 89°-96°; cheeks appear to be scaleless but sometimes with few to many, fine, embedded scales on lower 2/3; midline of thorax scaleless between pelvic ridges. Margin of anterior nostril encircled by a low flange with the flap extending towards posterior flap; flap shortens with increasing size.

Inhabits inshore, algae reefs, estuaries and in large lagoons with Algae-rubble habitats. Mainly common on rocky substrates (Ref. 48637). In contrast to S. fuscescens, this species seems to tolerate more turbid waters, occurring within the vicinity of river mouths especially around seagrass beds. Also occurs several kilometers offshore in deep, clear waters. Juveniles form very large schools in shallow bays and coral reef flats; school size reduces with size, with adults occurring in groups of 20 individuals or so. Herbivorous, feeds on benthic algae and to some extent on seagrass. Consumed as food; and have poisonous spines.