Longnose Filefish

Oxymonacanthus longirostris, is a filefish in the family Monacanthidae found on coral reefs in the Indo-Pacific Oceans.

Description

It has a long snout with a small upturned mouth. The body profile above and below the snout is concave. The body is pale bluish green with about eight longitudinal rows of small dark-edged yellow to orange spots. There is a dark spot on the caudal fin.

Distribution

Indo-Pacific: East Africa south to Maputo, Mozambique and east to Samoa, north to Ryukyu Islands, south to the southern Great Barrier Reef, New Caledonia, and Tonga. Replaced by Oxymonacanthus halli in the Red Sea.

Habitat

Occurs in clear lagoon and seaward reefs from 0.5 to at least 30 m. Found in pairs or small groups and nests near bases of dead corals, often on clumps of algae. Monogamous. Feeds exclusively on Acropora polyps. Feeding takes place throughout the day becoming less towards the evening.

Biology

Aggression is used commonly in courtship. Spawning commences when after swimming together in different tufts, the female concentrates on just one and begins to thrust repeatedly and pause. The male follows suit nuzzling the female. The female then drops into the algae and spawns, while the male releases the sperm beside her. The pair then swims back to their territory. They absorb and use chemicals in the Acropora coral they eat to take on its smell, which cloaks them from natural predators like cod. In addition to this trait, not observed among other vertebrates, they also use visual camouflage.