Threadfin Cardinalfish

Geographical Origin and Habitat: Tropical Indo-Pacific, distributed from the Red Sea and East Africa to Samoa and southern Japan. Inhabits calm lagoons and sheltered bays.

Taxonomy and Morphology: Member of the family Apogonidae. Features a deep, compressed body shape, large eyes, and a tall, thread-like first dorsal fin.

Social Behavior: Highly gregarious and peaceful. Forms large schools that hover closely around branching Acropora or Porites corals.

Coloration and Sexual Dimorphism: Translucent silver-blue body with metallic sheen. Decorated with thin vertical orange-yellow bars on the head, and blue rings around the eyes.

Aquarium Setup: Requires a peaceful marine aquarium of at least 100 liters with branching corals or structures to replicate its natural shelter.

Diet and Feeding: Carnivorous. Feeds on zooplankton, copepods, and small crustaceans. Accepts frozen cyclops, daphnia, brine shrimp, and small pellets.

Water Quality: Standard marine parameters: temperature 22-27 °C, pH 8.1-8.4, salinity 1.020-1.025, and stable water quality with moderate current.

Compatibility and Cohabitation: Highly peaceful and reef safe. Must be kept in schools of 5 or more specimens. Do not keep with aggressive or boisterous fish.

Aquarium Breeding: Paternal mouthbrooder; the male holds the fertilized egg mass in its mouth until hatching. Successful spawning is possible in mature tanks.

Risks and Diseases: Very low risk. Shy at first, but acclimates well. Vulnerable to predation by large tankmates due to its small size.