The orange spotted filefish or harlequin filefish, Oxymonacanthus longirostris, is a filefish in the family Monacanthidae found on coral reefs in the Indo-Pacific Oceans.
This eelpout, about 7 cm long, swims about in a darkened, chilled aquarium. When illuminated, It curls up in a ball and hangs motionless in the water. To a predator it may appear too large to swallow, or perhaps it resembles a jellyfish with stinging cells.
Juvenile vermilions are bottom-dwelling--their blotchy coloration may provide some camouflage in this environment. This individual, about 6 cm., is just starting to acquire the adult coloration. Depth 17 m.