Chelmon rostratus

Common Names: Copperband butterfly, beaked coralfish

Type Locality: Indian Ocean

Range: Western Pacific from India and Southeast Asia to the Ryukyu Islands and Australia

Taxonomic Troubles: Originally described as Chaetodon rostratus

Size: 18 cm (7 inches) TL

Preferred Water Chemistry: Tropical marine. Very sensitive to dissolved wastes

Difficulty: This species has a varied survival record, neither easy nor impossible to keep. Many die shortly after import due to improper car, and they can be very difficult to get feeding. Once established, they prove hardy.

Tank Setup: Needs a large tank with plenty of live rock as well as open swimming areas. Including one in a reef tank often leads to the loss of invertebrates. Certainly all fan or tube worms will fall prey, as may anemone and corals.

Feeding: An omnivorous grazer. They only seem to thrive in established tanks with plenty of live rock. Their elongated snout is used to poke into holes, extracting worms and other delicacies. They must have vegetable matter in their diet as well.

Breeding: No yet reported in the aquarium.

Fish Description

Laterally compressed with a long snout, silvery white background with a series of beige bars eded in blue and black. A prominent ringed ocellus (eye spot) on the dorsal, with the true eye camouflaged with a bar through it.


If you start with a healhty specimen, which you see feeding in the store, and if you provide pristine water conditions, plenty of room, and an appropriate diet, you can be successful with this species. Unfortunately we still see fish collected illegally with cyanide, and such animals may eat heartily but still die a couple of months later, waster with starvation due to non-functional digestive tracts. In addition, this species, like most butterflies, is very sensitive to shipping stresses and often fails to recover. Thus, the problem is much more with the fish's treatment than with the fish itself. Buying only healhty fish from reputable dealers who can provide a record of the chain of responsibility back to the collector (e.g., MAC-certified) will make an enormous difference with this or any other species.

This fish is often recommended to control the anemone Aiptasia. They may eat the pests, but not necessarily. If the outbreak is in a reef tank, adding a copperband runs the additional risk of having the fish prey on the desired invertebrates--perhaps instead of on the Aiptasia! Some aquarists recommmend offering the anemone to the fish while it's still in quarantine; if it won't eat them, there's no point risking putting it into the tank. As is the case with many reef fishes, the extent to which they will prey on sessile invertebrates in our reef tanks is unpredictable. Success or failure depends on the animal's learned food preferences, the diet offered to it, individual differences, and--it seems--sheer luck.

This is a delightful and beautiful species, best suited to a FOWLR setup, but make sure to start with a healthy and well-cared-for specimen.