Ring-tailed Cardinalfish

Geographic Origin and Biotope: Widespread in the Indo-Pacific, from the Red Sea and East Africa to the Line and Tuamotu islands, north to Japan, and south to the Great Barrier Reef. Inhabits reef ledges, caves, and coral overhangs at depths of 1 to 40 meters.

Taxonomy and Morphology: Belongs to the genus Apogon. Grows to a relatively large size for a cardinalfish, reaching a maximum length of 14 cm (5.5 inches). Features large black eyes with blue rings.

Social Behavior: Peaceful and nocturnal. Aggregates in loose groups inside caves during the day and emerges at night to forage.

Coloration and Sexual Dimorphism: Body is a brilliant golden-yellow or coppery-bronze. Characterized by a vertical black band encircling the tail base and blue horizontal lines running through the head. No visible sexual dimorphism.

Aquarium Setup: Needs at least 150 liters of tank volume with plenty of live rock arranged to create large, shaded caves and rocky overhangs. A secure lid is recommended.

Diet and Feeding: Carnivorous. Feeds on zooplankton and small benthic invertebrates. Feed meaty foods such as krill, mysis, brine shrimp, and protein pellets. Feeding should be done in the evening.

Water Quality: Demands clean and stable water: temperature 24-27°C (75-81°F), pH 8.1-8.4, specific gravity 1.022-1.025, GH 15-25, and KH 8-12.

Compatibility and Tankmates: 100% reef-safe. Peaceful community fish. May consume very small ornamental shrimp. Keep in pairs or small groups. Avoid keeping with aggressive predators.

Aquarium Reproduction: Paternal mouthbrooder. The male holds the egg clutch in his mouth until they hatch. Raising the larvae is highly complex.

Risks and Diseases: Very hardy. The main risk is keeping it with large piscivorous fish that can swallow it whole.