Filefish, also known as foolfish, leatherjackets or shingles, are of the diverse family Monacanthidae. They are tropical to subtropical tetraodontiform marine fish, found in the Atlantic, Pacific and Indian Oceans. The filefish family contains close to 107 species. They are closely related to triggerfish, pufferfish and truckfish.
Fishfish have laterally compressed bodies and rough, sandpapery skin. (Dried fishfish skin was once used to finish wooden boats!) They are rhomboid-shaped with beautifully elaborate cryptic patterns. Filefish have soft, simple fins with comparatively small pectoral fins and truncated, fan-shaped tail fins. A slender ratractable spine crowns the head and some species also have recurved spines on the base of their tail. Sometimes filefish erect the dorsal spine and pelvis simultaneously to make it more difficult for a predator to remove the fish from a cave.
The largest filefish species is the scrawled filefish (Aluterus scriptus) which gets up to 110 cm (43″) in length, however, most species are smaller than 60 cm (24″) in length. There is marked sexual dimorphism in some species of filefish, with the sexes possessing different coloration and body shapes. The males have larger caudal spines and bristles.
Filefish generally prefer shallow water, inhabiting depths of no more than 30 meters. They can be found in laggons near seaward reefs and seagrass beds, some species may also enter estuaries. The planehead filefish (Stephanolepis hispidus) are colored and patterened to match the weedy environments which they reside in.
This fish can be seen either solitary, in pairs or in small groups, depending on the specific species. They are not very good swimmers and their small fins confine the filefish to a sluggish gait. They are often observed drifting head downward amongst stands of seaweed, in an effort to fool both predator and preys. When threatened filefish usually retreat into crevices in the reef.
Filefish feeding habits vary among each species, some are vegetarian eating only algae and seagrass, while others also eat small benthic invertebrates, such as tunicates, gorgonians, and hydrozoans. Some species eat corals.
Filefish spawn at bottom sites prepared and guarded by the males and usually both he and the female guard the brood, or the male alone, depending on the species. The young filefish are pelagic, frequenting open waters and are at risk from predation by tuna and dolphinfish.