Can Black Ocellatus and Tanganyikan Clown Cichlid (Eretmodus) Live Together?

Both Black Ocellatus and Tanganyikan Clown Cichlid (Eretmodus) are semi-aggressive species with an aggression score of 7/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Both Black Ocellatus and Tanganyikan Clown Cichlid (Eretmodus) are highly aggressive, increasing the risk of violent confrontations.

Black Ocellatus and Tanganyikan Clown Cichlid (Eretmodus) both frequent the Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Additional behavioural considerations to keep in mind: Two territorial species may clash over territory, especially in smaller tanks.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Black Ocellatus and Tanganyikan Clown Cichlid (Eretmodus) to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations.

The safe temperature window for both species falls between 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

Both fish can tolerate a pH between 8 and 9. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 10–25 dGH. Regular testing will ensure conditions stay within this range.

To house Black Ocellatus and Tanganyikan Clown Cichlid (Eretmodus) together, plan for an aquarium of at least 100 litres with a minimum length of 90 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Sand (Sifters), Shells (Breeding/Hiding), Smooth Gravel (Sensitive Barbels), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Black Ocellatus prefers Low (Still Water) flow while Tanganyikan Clown Cichlid (Eretmodus) needs High (River/Stream) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.