Blackback Butterflyfish

The Black-backed Butterflyfish, also known as the Blackback Butterflyfish (Chaetodon melannotus), is a member of the butterflyfish family (Chaetodontidae) with a broad distribution across the Indo-Pacific region, ranging from the 🌊 Red Sea and East Africa to 🇼🇸 Samoa, southern 🇯🇵 Japan, and throughout 🇫🇲 Micronesia. This species can grow up to 18 cm in length and has a lifespan of up to 20 years. Notably, it exhibits a unique color change when startled or during nighttime, with the dorsal part of its body turning black and displaying two distinctive white patches.

Classified under the large subgenus Rabdophorus—potentially meriting recognition as a separate genus—the Black-backed Butterflyfish is closely related to the Spot-tailed Butterflyfish (C. ocellicaudus), and somewhat less so to the Yellow-dotted Butterflyfish (C. selene). These species share common characteristics, including an oval shape, silvery body with yellow fins and snout, diagonal stripes, and black markings around the eyes and on the caudal peduncle. Further relatives include the Saddle Butterflyfish (C. ephippium) and the Dotted Butterflyfish (C. semeion), whose evolutionary paths diverged early in the diversification of the Rabdophorus lineage.

These oviparous fish are typically observed among staghorn coral thickets and are less frequently found on exposed reef areas. Generally inhabiting waters between 4 and 20 meters deep, Black-backed Butterflyfish are usually solitary but may form pairs during the breeding season. Juveniles are often found inshore, either in pairs or small groups. Their diet primarily consists of soft and hard coral polyps. Within aquarium settings, the Black-backed Butterflyfish is considered relatively easy to maintain compared to other species within its genus.