The “false eye” on the flanks of this fish is much larger than the real one in its head. This is a classic example of a distraction pattern which misleads predators into aiming for the rear of the fish, rather than its head. Similar eye-like spots are seen in other fishes and many insects. This is an abundant species in the Caribbean and the Southern Gulf of Mexico. In the summer, young specimens drift up the Atlantic coast with plankton, as far north as New England. This species has been popular in public aquariums for more than a hundred years.
The Copperband or Beaked butterfly fish is a popular species, but can be a finicky aquarium inhabitant. By nature, the Copperband butterfly feeds on coral polyps, its long slender mouth perfectly suited for this task. In aquariums, the Copperband butterfly is often introduced as a “natural” pest control solution for nuisance anemones such as Aiptasia spp. The dark spot near back half of the dorsal fin is believed to be a “false eyespot” which can fool would-be predators into thinking the fish’s eye is on the opposite end, giving the fish a chance of escape.
Very few of these unique butterflyfish have ever been kept in North America. While many of their relatives are found across vast areas of the Pacific, this dramatically colored species is found only in the Izu and Ogasawara islands of southern Japan, where it can be very common. Because this is a plankton-eating butterflyfish, rather than a polyp-eater, it is one of the easier members of its family to maintain in aquariums.