Can Black Belt Cichlid and Celestial Pearl Danio (Galaxy Rasbora) Live Together?

Black Belt Cichlid is a semi-aggressive species (8/10), while Celestial Pearl Danio (Galaxy Rasbora) is peaceful (2/10). This notable difference means Black Belt Cichlid may occasionally assert dominance over Celestial Pearl Danio (Galaxy Rasbora).

Large aggression gap (6 points) between Black Belt Cichlid and Celestial Pearl Danio (Galaxy Rasbora) increases stress risk for the more peaceful fish.

Black Belt Cichlid and Celestial Pearl Danio (Galaxy Rasbora) both frequent the Middle (Open Water) and 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: Aggressive fish may bully and stress shy, slow-moving species.

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 Belt Cichlid and Celestial Pearl Danio (Galaxy Rasbora) to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations. A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

The safe temperature window for both species falls between 24°C and 26°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 7 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 8–15 dGH. Regular testing will ensure conditions stay within this range.

To house Black Belt Cichlid and Celestial Pearl Danio (Galaxy Rasbora) together, plan for an aquarium of at least 450 litres with a minimum length of 150 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), Driftwood (Digestion/Hiding), Plants - Densely covered. Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Black Belt Cichlid is a plant destroyer, which conflicts with Celestial Pearl Danio (Galaxy Rasbora)'s requirement for live plants. Compromise where possible or prioritise the more critical need.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

This pairing usually fails when the tank is treated like a standard mixed community and the caution flags are ignored. Black Belt Cichlid and Celestial Pearl Danio (Galaxy Rasbora) need extra room, more cover, and closer observation during the first few weeks so small aggression, feeding, or territory issues do not snowball into a long-term problem.