The coffinfish (B.melanostomus) has a flabby body and long tail that are both covered with small spines. It has a black mouth lining and an illicium (glossary) on the snout that can be lowered into a groove. This species grows to at least 10cm in length. B.melanostomus has been trawled in the Central to Eastern Indian Ocean at depths ranging from 1320m to 1760m. The name melanostomus comes from the Greek melanos meaning black and stoma meaning mouth. There are two genera in the family Chaunacidae; Bathychaunax and Chaunax. Bathychaunax differs from Chaunax by having a lower lateral line count, longer ilicium, a wider head, more widely spaced body spines and several skeletal characters.