Blackback Butterflyfish

Geographical Origin and Habitat: Widely distributed in the tropical Indo-Pacific, from the Red Sea and East Africa to Samoa, north to southern Japan, and south to the Great Barrier Reef. Inhabits shallow, coral-rich lagoons and seaward reefs.

Taxonomy and Morphology: Belongs to the family Chaetodontidae. Features a highly laterally compressed, disc-shaped body with a pointed snout. Reaches a maximum length of about 15-18 cm. The small, protractile mouth is adapted for picking food from crevices.

Social Behavior: Typically observed in stable pairs or as solitary individuals. They are territorial fish that constantly patrol the reef for food. In captivity, they are peaceful toward other families but can be territorial toward conspecifics.

Coloration and Sexual Dimorphism: Silvery-white body with fine black diagonal stripes. The upper back features a dark, dusky saddle. The fins are edged in bright yellow, and a black vertical band runs through the eye. No visible sexual dimorphism.

Aquarium Setup: Requires a mature marine aquarium of at least 300 liters (80 gallons) with ample open swimming space and extensive rockwork forming caves and overhangs. Water movement should be moderate to strong to simulate natural reef currents.

Diet and Feeding: Omnivorous with a strong natural preference for soft coral polyps. In captivity, weaning onto prepared foods can be challenging; offer fresh opened clams, mysis shrimp, and frozen preparations before introducing high-quality pellets or flakes.

Water Quality: Requires pristine, stable marine parameters: temperature 24-28°C (75-82°F), pH 8.1-8.4, salinity 1.020-1.025 SG, and near-zero nitrates. A high-performance protein skimmer is essential.

Compatibility and Cohabitation: Not reef-safe; will nip at stony and soft corals, anemones, and feather dusters. Suitable for FOWLR systems with peaceful to semi-aggressive tankmates like tangs, dwarf angels, and wrasses.

Aquarium Breeding: Breeding in home aquariums is undocumented. In nature, they are pelagic spawners, releasing buoyant eggs into the water column, which float with oceanic currents.

Risks and Diseases: Susceptible to external marine parasites such as Cryptocaryon irritans (marine ich) and Oodinium (velvet) under stress. Quarantine is highly recommended. Secure lid is advised as they can jump when startled.