Jewel Damselfish

Geographical Origin and Habitat: Widespread in the tropical Indo-Pacific, from the Red Sea and East Africa to the Line and Society islands, north to southern Japan, and south to Australia. Inhabits rocky seaward reefs and shallow lagoons at depths of 1 to 40 meters, associated with hard corals.

Taxonomy and Morphology: Member of the family Pomacentridae, genus Plectroglyphidodon. Features an oval, laterally compressed body with distinct scales. Reaches a maximum size of approximately 10 cm.

Social Behavior: Highly territorial and aggressive. Establishes a home territory around a rock crevice or coral head and defends it fiercely against fishes many times its size.

Coloration and Sexual Dimorphism: Dark brown to blackish body adorned with small electric-blue spots resembling jewels. Juveniles display a higher density of blue spots. No visible external sexual dimorphism.

Aquarium Setup: Demands an aquarium of at least 200 liters due to its extreme aggressiveness. Provide extensive rockwork structures to form visual barriers, helping other tank inhabitants escape its line of sight.

Diet and Feeding: Omnivorous. Feeds mainly on benthic algae and small invertebrates. In captivity, feed twice daily with frozen foods (mysis, brine shrimp), pellets, and spirulina-based preparations.

Water Quality: Exceptionally hardy and tolerant. Standard marine parameters: temperature 22-29°C, pH 8.0-8.5, specific gravity (SG) 1.020-1.025, GH 15-25, KH 8-12. Good filtration helps keep organic levels stable.

Compatibility and Cohabitation: Reef safe with corals. Not compatible with docile, small fishes, gobies, or blennies. Keep only with large, robust, and aggressive tankmates (e.g. large surgeonfishes, triggers). Introduce last to the tank.

Aquarium Breeding: Oviparous. Adhesive demersal eggs are laid on rock surfaces and guarded by the male until hatching. Captive rearing is difficult.

Risks and Diseases: The primary risk is physical injury inflicted on tankmates due to its aggressive behavior. Extremely resistant to disease and external parasites.