Blue Velvet Damselfish Cichlid (Pseudotropheus johannii)

Pseudotropheus johannii (now correctly placed in the genus Melanochromis by some authorities), the Johanni Cichlid, is one of the most striking examples of sexual colour dichromatism in freshwater fish. Males display a uniform, brilliant electric blue to blue-grey colouration across the entire body and fins — a vivid, metallic hue that earns the 'electric blue' descriptor. Females are a contrasting vivid orange-yellow, allowing instant identification by colour alone.

Endemic to Lake Malawi in East Africa, P. johannii belongs to the Mbuna group — the rock-dwelling cichlids of Malawi that evolved in the intensely competitive rocky littoral zone of one of Africa's Great Rift Valley lakes. Like all Mbuna, it is an aufwuchs feeder, grazing algae and associated microorganisms from rock surfaces.

The Johanni is an active and relatively aggressive Mbuna species. Males are highly territorial and will chase both rival males and females when not in spawning condition. Females are mouthbrooders — they incubate fertilised eggs in the buccal cavity for approximately 3 weeks before releasing small but fully formed fry.

Successful keeping requires a densely rockworked, Mbuna-specific aquarium with multiple territories and visual barriers to distribute aggression across a community of similar species. The dazzling blue-and-orange colour contrast of a mixed-sex group in a Malawi rock aquarium is one of the most dramatic spectacles in freshwater fishkeeping.

Tank Setup: Minimum 200-litre Mbuna aquarium with extensive rock piling from substrate to near the surface. Use crushed coral or aragonite substrate to maintain alkaline pH. Create multiple distinct cave territories. Pack fish densely — overcrowding counterintuitively reduces individual aggression by spreading it across many fish.

Water Parameters: Temperature 24–28°C; pH 7.8–8.5; GH 12–20 °dH; KH 8–14 °dH. Alkaline, hard water reflecting Lake Malawi chemistry. Do not use peat or blackwater additives — incompatible with Mbuna requirements.

Feeding: Omnivore/herbivore (aufwuchs diet). Feed spirulina-based flake, vegetable-based cichlid pellets, blanched vegetables. Supplement sparingly with protein. High-protein diets cause Malawi Bloat — a deadly internal disease.

Tank Mates: Keep with other Mbuna cichlids: Labidochromis caeruleus (Yellow Lab), Pseudotropheus species, Iodotropheus, and similar Melanochromis. One male Johanni per tank. Keep away from Peacock cichlids and Haplochromines.

Behaviour: Highly territorial males. Mouthbrooding females require a quiet period to incubate eggs — consider a separate breeding tank for safe fry release. Aggression is normal and constant — provide visual barriers.

Health: Prone to Malawi Bloat if fed high protein diet. Maintain alkaline chemistry and spirulina-based feeding. Weekly 25–30% water changes essential.