 The inside of the mouth and gill cavities are black.Juveniles are believed to be mesopelagic, living at depths from .The black scabbardfish is bathypelagic by day, but moves upwards in the water column at night to feed at middle depths on crustaceans, cephalopods, and other fishes, mostly grenadiers, codlings (family Moridae) and naked heads (family Alepocephalidae).