FilefishesMonacanthidae

Filefishes (Monacanthidae) are rhomboid-shaped, laterally compressed fishes recognized by their rough, sandpapery skin, from which their common name derives. Their head features a small, terminal mouth with specialized incisor teeth and an often tapered snout. A single, retractable dorsal spine is secured by a smaller second spine, a feature that gave the family Monacanthidae its name, meaning "one thorn" in Greek. Most species grow to less than 60 cm (24 in) in length, though some can reach 110 cm (43 in). Their colour patterns are diverse, often cryptic, with some species exhibiting sexual dimorphism.

Filefishes inhabit shallow waters down to 30 m (100 ft), found on seaward reefs, in lagoons, and among seagrass beds. They move slowly, encountered solitary, in pairs, or small groups. Some species drift head-downwards, camouflaged among vegetation. When threatened, they retreat into reef crevices, erecting their dorsal spine and a bony pelvic dewlap to wedge themselves securely. Their diet varies across species, including algae, seagrass, and benthic invertebrates such as tunicates, gorgonians, hydrozoans, and some corals.