Millet butterflyfish stripe runs from above the eye to the base of the operculum, and there is a large black patch on the caudal peduncle. This fish is endemic to the Hawaiian Islands and the Johnston Atoll, and is found down to depths of at least . Its habitats include coastal fringing reefs, outer reefs and lagoons. The millet butterflyfish is a schooling species found in mid-water that feeds on zooplankton. It also feeds opportunistically on polychaete worms and other small invertebrates on the seabed. Food is drawn into the mouth by rapid suction. It does not seem to be territorial but
Upeneus moluccensis anal fin. The caudal fin is deeply forked. The chin bears a pair of barbels which do not extend past the margin of the preoperculum. The upper and lower jaws, the palatine and the vomer are covered in brush-like or villiform teeth. The back is pinkish-red in colour contrasting with the white belly, from which it is separated by single longitudinal yellow stripe which runs from the operculum to the caudal fin peduncle. The dorsal fins are yellow in colour with 3 parallel red bars while the pectoral find is a similar colour but lacks markings and the pectoral fin