Chelmon rostratus, the copper banded butterflyfish, has long been a reef fish icon. It seems like whenever you see a painting of a reef scene or a shower curtain with a fish motif, there he is — Mr. Copper-banded Butterflyfish. While it may look good in the bathroom or on the living room wall, this fish has not always looked so hot in the home aquarium. Not because it is not colorful, but because it often wastes away and dies in captivity.
Before the popularity of the reef aquarium, this species was even more destined for early death. Fortunately, the copper banded tends to do much better in the reef aquarium, and not only is it more likely to thrive in the reef aquarium, it can also fill an important utility role.
Difficulty: This fish is not for everyone. The biggest hurdle with this species is getting it enough to eat. The copper banded butterflyfish can often be finicky about ingesting normal aquarium foods, especially if it is placed in a new and bare fish-only aquarium. The species will always do the best in a mature reef aquarium where water quality is likely to be better and there are worms and sessile invertebrates that it can nibble on.
Physical description: This butterflyfish is easily recognized by its extremely long snout and its coloration (bright coppery orange stripes, the distinct eye spot on its dorsal fin, and the black band on its caudal peduncle). The copper banded butterflyfish reaches a maximum length of 8 inches. The margined butterflyfish (Chelmon marginalis) is similar to Chelmon rostratus overall but lacks the central body stripe and has no black saddle on the caudal peduncle. This species is consistently hardier than Chelmon rostratus because it is only collected in Australia. Fish collected from Australia tend to be handled with greater care than those from the Philippines or Indonesia.
Range: The Chelmon rostratus occurs in the Andaman Sea to Papua New Guinea and the Great Barrier Reef. This fish is a resident of fringing reefs, lagoon patch reefs and can occasionally be found in estuaries. The copper banded butterflyfish tends to prefer more turbid, sheltered reefs than some of its chaetodontid cousins. While many butterflyfishes feed on corals, this fish uses its long snout to snip off tubeworm tentacles. The copperbanded butterflyfish will also pluck small crustaceans off the substrate. Adult Chelmon rostratus are found singly or in pairs.
Compatibility: The copper banded butterflyfish is peaceful toward tankmates. They will fight with each other, especially if both fish are males. Male Chelmon rostratus will ram their heads together and begin pushing against their rival. When one gets the best of the other, the losing fish will swim off (that can be hard in the confines of an aquarium). If the copper banded butterflyfish is picked on by larger, more aggressive fish, it will hide behind the reef decor or hover in the corner of the aquarium. For this reason, place your Chelmon rostratus in the tank and wait until it is eating well before adding potential bullies (such as butterflyfish, angelfish, large damsels and triggerfish). It is possible that your copperbanded butterflyfish will pick at corals (namely “polyps” and large-polyped stony corals), but if well-fed, it is usually well-behaved.
This fish is certainly a threat to tube worms of any type (e.g., fan worms, Christmas tree worms). It is often employed by reefkeepers to help control outbreaks of the noxious glass sea anemone (Aptasia). That said, some individuals are better at this task than others.
Aquarium conditions: The copper banded butterflyfish should be provided with plenty of open swimming space as well as good crevices and caves to hide in if it feels threatened. Adults can be housed in a 75-gallon aquarium or larger, and the water parameters should be as follows: pH at 8.1 to 8.4, the specific gravity of 1.019 to 1.025, and water temperature between 76 to 82 degrees Fahrenheit.
Breeding: The copper banded butterflyfish will not spawn in captivity.