Filefishes

Scientific name : Monacanthidae

Monacanthidae family includes a hundred species, mostly tropical, not very well known and often unobserved. Few species have uniqie colour patterns, but most of them are well camouflaged, have variable colour matching the environment, can change colour quickly for camouflage and are not easy to identify. Furthermore some species do not like to interact with divers, and hide carefully when a human observer is close, that make observation even more difficult.
The body is polygonal, laterally compressed. The mouth is small. Characteristic a dorsal spine, normally followed by a second one, shorter, that can be folded backward. Ventral fins are fused together in a membrane that can be raised, with another spine at the end.
The small scales, each one with a filament, can give the skin a velvety or rough texture (hence the name of file fishes).
They swim by undulating movements of the symmetrical dorsal and anal fins.
File fishes live in many different environments, many species being associated with corals on the reef front and external reef, other living on sandy or seagrasses covered bottoms in bay or lagoon.
Many species feed on benthic invertebrates, few on Plankton. Some are coral feeders.
The eggs are normally benthic, laid on the bottom and in some species the male defends a nest.
File fishes are very similar to the related family of trigger fishes. They have normally a more compressed shape (trigger fishes are mopre robust) and the first dorsal fin is made by an obvious spine followed by a very short one (trigger fishes have 3 visible spines).
Few species mimic the small puffer fishes (Canthigaster). They are identified by the compressed shape, by the dorsal spine (missing in the puffer fishes) and by the longer dorsal and anal fins.
Although the more bully trigger fishes are by far better known, the discreet file fishes have a more than double number of living species.