Chaetodon falcula is one of 88 members of the genus Chaetodon, which together with 11 additional genera make up the butterflyfishes family (Chaetodontidae) in which a total of 129 species are currently described. This species inhabits the tropical waters of the Indian and Pacific Oceans, from the east coast of Africa to Indonesia and the island of Java. It inhabits the outer edges of coral reefs, in areas with strong currents or even inside coral lagoons, and always in relatively shallow waters being rare to observe them beyond 15 meters deep.
The body of Chaetodon falcula is oval and laterally compressed, with an elongated rostrum and a concave dorsal profile. They reach sizes up to 20 cm long. At the end of the snout there is a small mouth with numerous small teeth. The dorsal fin is continuous and has 12-13 spines and 23-25 soft rays, while the anal fin has 3 spines and 20-21 soft rays. The posterior margins of the dorsal and anal fins are much more developed than the anterior ones, joining with the caudal fin to give an oval shape to the body of the specimen.
The coloration of the body of Chaetodon falcula is white, with a series of narrow vertical gray lines. The dorsal, anal and caudal fins are colored in bright yellow and orange. Above the eyes there is a vertical black line across the head, and on the dorsal fin there are two characteristic black spots of more or less triangular shape. It also has a vertical black line at the base of the caudal fin.
It is usual to observe specimens of Chaetodon falcula either in pairs or in small groups of at most 15-20 specimens. The feeding of this species is strongly conditioned by the specialization of its snout and its small mouth. Among the prey we find small invertebrates and polyps of some corals.
The reproduction of Chaetodon falcula occurs just before sunset, at which time schools of specimens release eggs and sperm into the water column for fertilization to occur. The resulting larvae are planktonic and will be disseminated by the dominant currents in the area.
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