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
Lanternfish pectoral fins, usually with eight rays, may be large and well-developed to small and degenerate, or completely absent in a few species. In some species, such as those of the genus "Lampanyctus", the pectorals are greatly elongated. Most lanternfish have a gas bladder, but it degenerates or fills with lipids during the maturation of a few species. The lateral line is uninterrupted. In all but one species, "Taaningichthys paurolychnus", a number of photophores (light-producing organs) are present; these are paired and concentrated in ventrolateral rows on the body and head. Some may also possess specialised photophores on the caudal peduncle,