Marine Betta (Comet)

Geographic Origin and Biotope: Widespread in the Indo-Pacific (from the Red Sea and East Africa to Tonga and southern Japan). Populates coral reefs, hiding by day in caves or crevices.

Taxonomy and Morphology: Comet or Marine Betta (Calloplesiops altivelis). Beautiful marine fish (Plesiopidae family). Reaches 20 cm (8 inches). Characterized by enormous pelvic, dorsal and anal fins, and a fake "eye" (ocellus) on the base of the dorsal fin.

Social Behavior: Very shy nocturnal predator. Spends daylight hours hidden in the caves of the rockwork. If frightened, it slips into a crevice leaving its tail with the ocellus exposed, mimicking the head of a dangerous moray eel (Gymnothorax meleagris).

Coloration and Sexual Dimorphism: Spectacular coat: dark brown or black background dotted with hundreds of tiny white or blue spots, resembling a starry sky. No obvious sexual dimorphism.

Aquarium Setup: Marine aquarium of at least 300 liters (80 gallons). A rich live rockwork forming deep and dark caves is indispensable. Moderate lighting or abundant shaded areas.

Diet and Feeding: Pure carnivore. Often difficult to wean to inert food. Feed with mysis shrimp, krill, pieces of squid and fish or clam meat. May ignore dry food.

Water Quality: Requires stable marine parameters: salinity 1.023-1.025, pH 8.1-8.4, excellent skimming to remove the organic load of protein meals.

Compatibility and Tankmates: Reef-safe "with caution": it does not touch corals, but will devour any ornamental shrimp (Lysmata, Thor) or small fish (small gobies) that passes by. Coexists well with angelfish, surgeonfish and moray eels.

Aquarium Reproduction: Rare but possible. Oviparous species that lays adhesive eggs in caves. The male guards and ventilates the brood until hatching. Weaning the tiny marine larvae is for experts.

Risks and Diseases: Very robust fish once acclimated and weaned. The main risk is death from starvation in the first weeks if stressed by overly aggressive tankmates who steal its food.