One-spot Damselfish

Geographic Origin and Biotope: Indo-West Pacific: Red Sea and East Africa to Fiji, north to southern Japan, south to Australia. Inhabits shallow waters (0-3 meters) on reef flats, rocky coasts, and tide pools.

Taxonomy and Morphology: Member of the family Pomacentridae. Reaches a maximum length of 10 cm. Oval, laterally compressed body, typical of territorial damselfishes.

Social Behavior: Highly aggressive and territorial. Defends its chosen territory aggressively against any fish, especially other damselfish or food competitors.

Coloration and Sexual Dimorphism: Dull brown or olive-grey body, featuring a prominent black spot at the base of the rear dorsal fin. Juveniles are brighter with neon blue stripes on the head. Sexes look alike.

Aquarium Setup: Provide a tank of at least 120 liters with plenty of live rock to create caves and territories. This helps focus its aggression and provides security.

Diet and Feeding: Omnivore. Primarily an algae eater in the wild. In the aquarium, it readily consumes flake food, pellets, spirulina, and frozen foods like mysis and brine shrimp.

Water Quality: Extremely hardy and tolerant of varying water parameters. Keep temperature at 22-28°C, pH 8.0-8.5, and salinity at 1.020-1.025 SG.

Compatibility and Tankmates: Avoid keeping with peaceful, slow, or shy fish. Best kept as a single specimen in a community tank with larger, robust, and semi-aggressive species.

Aquarium Reproduction: Demersal spawner. Eggs are attached to a hard surface and guarded by the male, who becomes highly aggressive. Rearing larvae requires tiny live foods.

Risks and Diseases: Very resistant to diseases. The primary risk is its high level of aggression, which can cause stress or physical damage to tankmates.