Appearance
The blacktail butterflyfish (C. austriacus), melon butterflyfish (C. trifasciatus), and oval butterflyfish (C. lunulatus) are similar in coloration. The former has black caudal and anal fins, while the latter is an Indian Ocean species and has a more conspicuous back patch below the dorsal fin and a mainly yellow anal fin. Chaetodon lunulatus can grow up to 14 cm long. It has about 13–14 dorsal spines, 20–22 dorsal soft rays, three anal spines, and 18–21 anal soft rays.

