Histiopterus typus, the sailfin armorhead or threebar boarfish, is a species of armorhead native to the Indian Ocean and the western Pacific Ocean. It is an inhabitant of rocky reefs in deeper waters of 40 to 421 m (131 to 1,381 ft) in depth. This species grows to a length of 42 cm (17 in), though most are only around 20 cm (7.9 in). It is a commercially important species, and is the only known member of its genus.