Fan-Bellied Leatherjacket

Monacanthus chinensis

The fan-bellied leatherjacket (Monacanthus chinensis) is a species of filefish in the family Monacanthidae. Adults reach about 38 cm with a laterally compressed body, a prominent first dorsal spine, and a distinctive expandable fan-like ventral flap. Coloration is variable, ranging from mottled brown and green to olive with darker blotches, providing excellent camouflage among seagrass. This species inhabits seagrass beds, soft sediment areas, and coastal reefs at depths of 1-50 meters throughout the western Pacific and eastern Indian Ocean. Fan-bellied leatherjackets feed on a variety of organisms including small invertebrates, algae, and seagrass. They use their specialized expandable belly fan in social displays and to appear larger to predators. Their excellent camouflage abilities make them challenging to spot among vegetation, rewarding divers with keen observation skills.