Black-axil Chromis

Geographic Origin and Biotope: Indo-Pacific: East Africa to the Line and Tuamotu Islands, north to southern Japan, south to Australia. Schooling above branching coral heads.

Taxonomy and Morphology: Member of the family Pomacentridae. Reaches 12 cm in length. Distinguished from Chromis viridis by a black blotch at the pectoral fin base.

Social Behavior: Highly peaceful, active schooling fish. Requires a group to show natural behavior and prevent stress. Retreats into branching corals when threatened.

Coloration and Sexual Dimorphism: Iridescent blue-green body coloration. Features a distinct black mark on the axil of the pectoral fin. No visible sexual dimorphism.

Aquarium Setup: Needs a tank of at least 150 liters with plenty of open swimming area and branching corals or rocks for hiding.

Diet and Feeding: Omnivore. Feeds on zooplankton. Provide multiple small feedings daily of mysis, brine shrimp, marine flakes, and pellets to maintain health.

Water Quality: Standard marine conditions: temperature 22-26°C, pH 8.1-8.4, salinity 1.020-1.025 SG. Appreciates moderate to strong water flow.

Compatibility and Tankmates: Extremely peaceful. Ideal for reef tanks. Safe with corals and invertebrates. Do not keep with large predatory species.

Aquarium Reproduction: Demersal spawner. Males construct nests and guard the eggs. The pelagic larvae are very difficult to raise in home systems.

Risks and Diseases: School size must be sufficient (5+); in too small groups, dominant individuals may systematically harass the weakest.