Filefishes belong in the "Family Monacanthidae" and consisting of 31 genera, and 95 species. They are similar to Triggerfishes at first glance being similarly deep and flattened sidewise, with the same peculiar profiles, small terminal mouths, projecting incisor teeth, eyes set high up, very stout dorsal spines, and short gill openings; also in the fact that the ventral fins are either lacking altogether or at least are reduced to a single short blunt movable spine at the end of the very long pelvic bone, forming a keel-like continuation of the general ventral profile of the head and connected with that of the belly by a dewlap of skin. The filefishes differ from triggerfishes in having only one dorsal spine instead of three, and in the fact that their scales are so minute that the skin is velvety to the touch although very tough. Most of the species are tropical or subtropical.
Filefishes are slow movers, do not do well in aquariums with swift water movement, have extremely abrasive skin and are often called "leatherjackets" because of their skin texture. The diet of Filefishes consist mainly of amphipods, polychaetes and molluscs.