The Raccoon butterflyfish, Chaetodon lunula, also known as crescent-masked or Lunule butterflyfish, is a butterflyfish of the family Chaetodontidae found in the Indo-Pacific oceans from East Africa to the Hawaiian, Marquesan, and Ducie islands, north to southern Japan, south to Lord Howe and Rapa islands, and also in the southeast Atlantic from East London, South Africa, at depths down to 98.43 ft (30 m). Its length is up to 7.87 in (20 cm).
The Raccoon butterflyfish is a nocturnal species that is usually in pairs or small groups in warm, shallow reef flats of lagoon and seaward reefs. Juveniles occur among rocks of inner reef flats and in tide pools. Adults feed mainly on nudibranchs, tubeworm tentacles, and other benthic invertebrates including algae and coral polyps.
The Raccoon butterflyfish is generally not aggressive towards other fish, with the exception of lionfish and triggerfish. In captivity, the typical lifespan of a Raccoon butterflyfish is 5 to 7 years. In a confined environment, the Raccoon butterflyfish is prone to developing cryptocaryon.
Reproduction is oviparous, with pairs forming during breeding.