Eastern Triangular Butterflyfish

Geographical Origin and Habitat: Western Pacific Ocean, distributed from Indonesia and the Philippines to northern Australia and New Caledonia. Inhabits shallow, coral-rich reefs with Acropora table corals.

Taxonomy and Morphology: Member of the family Chaetodontidae. Exhibits a unique triangular body shape and deep body profile that distinguishes it from its relatives.

Social Behavior: Highly territorial and aggressive toward other butterflyfishes. Typically swims in stable pairs, actively defending its feeding territory from rivals.

Coloration and Sexual Dimorphism: Cream-colored or pale yellowish body with multiple thin, dark chevron-like bars on the sides. The tail is black with a thin yellow margin.

Aquarium Setup: Requires a large, specialized reef-style aquarium of at least 300 liters containing extensive branching or table Acropora coral colonies.

Diet and Feeding: Obligate corallivore, feeding exclusively on Acropora polyps and mucus. Almost impossible to keep in home aquariums unless fed live corals or successfully trained.

Water Quality: Demands pristine marine conditions: temperature 22-27 °C, pH 8.1-8.4, salinity 1.020-1.025 with zero organic waste, strong skimming, and high water flow.

Compatibility and Cohabitation: Highly aggressive toward other butterflyfishes. Not reef safe. Best housed in large fish-only systems with robust, non-competing tankmates.

Aquarium Breeding: Reproduction in home aquariums is undocumented. Spawns pelagic eggs, and larvae spend weeks drifting in open ocean currents before settling.

Risks and Diseases: Very high risk of starvation in captivity. Recommended only for public aquaria or expert hobbyists capable of providing live corals for food.