约翰黑丽鱼

Overview

Melanochromis johanni shows clear sexual color differences: males are blue-black with bright blue stripes, while females are orange. It is less aggressive than many congeners, but still has substantial aggression and conspecific territorial conflict.

Distribution & habitat

Endemic to Lake Malawi, it occurs around Masinje Rocks and Cape Ngombo, usually in relatively shallow rocky coastal water.

Aquarium setup

A tank around 90 × 45 × 38 cm provides a reference. Rock piles should create numerous caves with small open swimming areas. Sand and good oxygenation are appropriate. Plants are eaten, so do not depend on them as the main shelter structure.

Diet & feeding

Most suitable foods are accepted. Plant ingredients such as spirulina flakes and blanched spinach should form a substantial share, supplemented with live and frozen foods. Keep the overall menu varied.

Behaviour & compatibility

Appropriate similarly sized mbuna are possible companions. Some gentler cichlids of comparable size may also coexist, but this is a conditional option rather than a general assurance. Males are aggressive and territorial toward their own species. Several females per male are preferable, and multiple males require a larger aquarium.

Denser mbuna groups are sometimes used to distribute aggression, but must be balanced with filtration, oxygen and swimming room. Avoid breeding communities containing other Melanochromis because of hybridization risk.

Sexual dimorphism

Males have a blue-black background with bright blue stripes and are usually slightly larger. Females are orange. The comparatively dark dominant male also helps distinguish this species from the bluer Melanochromis cyaneorhabdos.

Breeding

Females mouthbrood and reproduction is generally relatively straightforward. A dedicated aquarium around 90 cm long can house one male and at least three females with flat stones and open bottom. Approximately pH 8.2–8.5 and 25–26.5 °C are breeding references, with varied live, frozen and plant foods for conditioning.

The male prepares a site and displays. The female immediately collects her eggs and receives sperm while responding to his anal-fin egg spots. She broods for about three weeks without eating. Stress or poorly timed relocation can cause release or consumption of the clutch, while a long absence may affect social rank. Avoid unnecessary early movement.

Fry can eat brine-shrimp nauplii upon release. The female generally guards them for about another week and retrieves them into her mouth when threatened.

Notes

The trade name “electric blue johanni” is sometimes misapplied to the similar M. cyaneorhabdos. Use actual identity and sexual color differences rather than the sales label alone.