Fish atlas

Geographical Origin and Habitat: Widely distributed throughout the tropical Indo-Pacific, spanning from the eastern coast of Africa and Madagascar to the Ryukyu Islands, the Great Barrier Reef, the Marshall Islands, and the Tuamotu islands. It inhabits sheltered coastal reefs, lagoons, and outer reef slopes at depths of 2 to 15 meters, hiding in caves or among branching Acropora corals during the day.

Taxonomy and Morphology: Belongs to the order Perciformes, family Apogonidae, subfamily Apogoninae, and genus Cheilodipterus. Described by Smith in 1961. It features an elongated body, two separate dorsal fins, and large eyes characteristic of nocturnal predators. It is distinguished by a large mouth lined with prominent, sharp canine teeth. Adult size is 12-15 cm (4.7-6 inches).

Social Behavior: Primarily nocturnal and solitary as adults, while juveniles may form small loose aggregations near staghorn corals. During the day, it hovers nearly motionless in shaded caves or overhangs. It displays intraspecific aggression in smaller tanks and will readily hunt smaller fish and crustaceans.

Coloration and Sexual Dimorphism: The body has a silver-gray to pinkish-tan background marked with 8 to 10 dark brown or black horizontal stripes. The caudal peduncle features a yellow patch with a distinct dark spot at the center. There is no visible external sexual dimorphism; sexes can only be distinguished during spawning.

Aquarium Setup: Requires an aquarium of at least 250 liters (65 gallons) for a single specimen or a mated pair. The aquascape must feature plenty of live rock arranged to create deep caves, overhangs, and shaded spots where the fish can seek shelter from bright lights during the day. Dimmable LED lighting with a moonlight phase is ideal.

Diet and Feeding: Carnivorous predator. Must be fed a diet of fresh or frozen meaty foods such as mysis shrimp, krill, chopped shrimp, pieces of fish, squid, and silversides. They rarely accept dry flakes or pellets. Feeding should take place during the evening or with the lights dimmed, once or twice daily.

Water Quality: Demands stable marine water parameters. Keep temperature at 24-28°C (75-82°F), pH 8.1-8.4, specific gravity 1.020-1.025, and KH 8-12. Nitrates and phosphates should be kept low. A high-performance protein skimmer is highly recommended to manage the high organic load from their meaty diet.

Compatibility and Cohabitation: Can be safely housed with medium to large, semi-aggressive fish such as tangs, angels, larger wrasses, and hawkfish. Absolutely avoid housing them with small gobies, firefish, neon damselflies, or ornamental shrimps (like Lysmata), as these will be quickly swallowed. Avoid hyperactive tankmates.

Aquarium Breeding: Extremely rare in home aquaria. Similar to other cardinalfish, they are paternal mouthbrooders. After fertilization, the male collects the egg mass into his mouth and carries them for about a week until hatching, during which time he does not feed. The newly hatched fry require rotifers and copepod nauplii.

Risks and Diseases: Relatively hardy once acclimated but vulnerable to transport stress and sudden temperature drops. Susceptible to common marine parasites such as Cryptocaryon irritans and Oodinium. Starvation can occur if highly active diurnal tankmates consume all the food before the cardinalfish emerges to feed.