Heniochus monoceros, belongs to the order of Perciformes and family of Chaetodontidae (Butterflyfishes).It is commonly known as the Bannerfish, Masked Bannerfish, Masked Coachman, Pennant Coralfish, or Unicorn Pennant Coralfish. This fish has a silvery white overall body colour and a protrusion that resembles a small horn on its forehead. It has two dark broad diagonal bands on its body. The first band starts at its mouth and covers its snout and eyes. The second band is in the middle of its sides. Its dorsal, caudal and anal fins are yellow. It has a total of 12 dorsal spines, 24 to 27 dorsal soft rays, 3 anal spines and 17 to 19 anal soft rays.
This species is present across the Indo-Pacific region. It is found in areas rich in corals, lagoons and outer reefs. Adults can be solitary, in pairs or in large groups. Distinct pairs are formed during breeding. Juveniles are solitary. Its diet consists of worms, crabs and other invertebrates.
According to the IUCN Red list, this species is categorized as being of ‘Least Concern’. It is collected for aquarium trade which is a potential threat. No conservation measures are in place for this species. It is present in many MPAs.
This species can reach a maximum recorded length of 24cm.