Copperband butterflyfish

Chelmon rostratus is a striking marine fish (family Chaetodontidae) found in the tropical Indo-West Pacific, from the Andaman Sea through Southeast Asia to northwestern Australia, Japan, and Papua New Guinea. Adults reach about 15–20 cm in length and are immediately recognizable by their tall, laterally compressed body, extremely elongated tubular snout, and vivid coloration: 4–5 bright orange-copper vertical bands edged in black on a pearlescent white body, with a prominent dark ocellus (false eyespot) ringed in white on the posterior dorsal fin. The long snout is an adaptation for probing crevices in coral reefs and rocky substrates to extract small invertebrate prey—polychaete worms, small crustaceans, and coral polyps. They also feed on Aiptasia anemones, making them valued in the marine aquarium hobby for pest anemone control. C. rostratus inhabits coral reefs, rocky shores, and estuarine areas, often near structures with abundant crevices. They are typically solitary or found in pairs. Reproduction involves pelagic spawning; eggs and larvae are planktonic. In aquariums, they are considered moderately difficult to maintain due to their specialized feeding habits and sensitivity to water quality. The species is popular in the ornamental fish trade but is not considered threatened in the wild due to its broad distribution.