Mertens' Butterflyfish

Mertens' Butterflyfish is a delicate and beautiful species found across the Pacific Ocean, particularly around oceanic atolls and outer reef slopes. The body features a white to pale gray background with fine chevron markings on the flanks, while the posterior portion of the body and tail are a vivid orange to reddish hue. A black eye band and darker dorsal region complete the attractive color pattern. This species is typically found at moderate depths along exposed reef walls and drop-offs.

This is one of the more difficult butterflyfish to maintain in captivity, as it is an obligate coral feeder in the wild, subsisting primarily on coral polyps and coral mucus. Many specimens refuse prepared foods entirely, and successful long-term maintenance often requires a dedicated keeper willing to offer a constant rotation of live and frozen foods. Starting with live blackworms, live brine shrimp, and clam on the half shell may help initiate feeding, though some individuals never fully transition to captive diets.

Mertens' Butterflyfish is absolutely not reef safe and will devour coral polyps if placed in a reef system. It is strictly recommended for experienced aquarists with well-established fish-only systems who are prepared for the feeding challenges this species presents. Keep singly and with peaceful, non-competitive tankmates to give it the best chance of thriving.