The sailfin armourhead (Histiopterus typus), also known as the threebar boarfish, is a species of marine ray-finned fish, an armourhead from the family Pentacerotidae which is native to the Indian Ocean and the western Pacific Ocean. It is an inhabitant of rocky reefs in deeper waters of 40to in depth. This species grows to a length of 42cm (17inches), though most are only around 20cm (10inches). It is a commercially important species, and is the only known member of its genus.