Calvus Cichlid

Geographic Origin and Biotope: Endemic to Lake Tanganyika in East Africa. Stations almost exclusively in deep and steep rocky habitats ("rocky shores"), dwelling in vertical crevices, caves and dark ravines to ambush prey.

Taxonomy and Morphology: Unmistakable cichlid with a very high and extraordinarily laterally compressed body ("thin as a blade"), adapted to slip into the narrowest rock cracks. It possesses a sloping cranial profile and strong jaws. Reaches 15 cm (6 inches) in length (males).

Social Behavior: Stealthy ambush predator. Extremely static, shy and lethargic: stations motionless upside down or obliquely for hours waiting for prey to pass by. Aggressive and territorial only towards its own male conspecifics.

Coloration and Sexual Dimorphism: Base color varying from pearl-white to dark ink black, crossed by fine vertical bands and countless pearly dots that stand out on the flanks. Males grow twice as large as females (who stay around 8-10 cm) and possess much more extended pelvic and dorsal fins.

Aquarium Setup: Tank starting from 150 liters (40 gallons). It is vital to reproduce a "rock wall" by stacking rocks to form narrow holes, caves and vertical crevices. Calcareous sand bottom. The lighting must be dim or shielded to encourage them to come out of hiding.

Diet and Feeding: Pure carnivore specialized in hunting small crustaceans and other people's fry. In the aquarium it gladly accepts sinking protein granules, mysis, krill, brine shrimp and bloodworms. Carefully avoid plant-based feeds that the intestine does not tolerate.

Water Quality: Requires strictly African water chemistry (Lake Tanganyika): strongly alkaline pH (8.0-9.0), hard water (GH 10-20), total absence of organic pollutants. They tolerate sudden drops in pH or the accumulation of nitrates very badly (max 20 ppm).

Compatibility and Tankmates: Relatively peaceful with other Tanganyika cichlids of different nature and shape (Cyprichromis, Neolamprologus, Julidochromis), provided they do not fit in its mouth. Warning: it is a ruthless nocturnal predator of fry and small fish.

Aquarium Reproduction: They lay their eggs inside large empty snail shells (e.g. Neothauma) or in the most inaccessible cracks. The minute female barricades herself inside guarding the eggs (up to 200), while the large male guards the outside entrance of the cave.

Risks and Diseases: Very robust fish due to the thick armor of hard scales. Deaths are linked to intoxication from nitrogenous waste (nitrites) in immature tanks or to intestinal blockages resulting from an incorrect diet or one too poor in animal fibers (chitin of crustaceans).