(Adult) Blue boxfish with a hump on the snout, dirty blue color with faint spots, faint yellow markings on the head and a yellow tail base. (Subadult) Small hump on the snout, yellow to brown color with dark ringed blue spots, fins are blue with small black spots, may have yellow or blue line markings. (Similar to Rhynchostracion nasus, but lacking the many black spots on the body). (Juvenile) Bright yellow with black spots, spherical body shape, hump on the snout is absent.
Unassessed by the IUCN Red list, fairly common species in tropical waters.
Indi-Pacific. Persian Gulf, Red Sea and Eastern Africa to the Hawaiian and Tuamoto islands. They inhabit lagoon and semi-sheltered seaward reefs. Juveniles are often found among Acropora corals. Small juveniles are secretive and hide under coral blocks and in narrow crevices. They can be found in a wide depth range of 1-280 meters, but usually in 1-50 meters.
Mating occurs in harems. Males mate with 2 to 4 females.
Up to 45cm.
They feed on algae, but are also known to feed on invertebrates, mollusks, sponges, polychaete worms, crustaceans, and fish.
The Red Sea population differs slightly in coloration and has been known as Ostracion argus; closely related to Ostracion immaculatus from southern Japan. Southeast Atlantic: south coast of South Africa