Can Boeseman's Rainbowfish and Cairns Rainbowfish Live Together?

Both Boeseman's Rainbowfish and Cairns Rainbowfish are peaceful species with an aggression score of 2/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Boeseman's Rainbowfish and Cairns Rainbowfish both frequent the Top (Surface) and Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Worth noting: Boeseman's Rainbowfish is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 26°C and 26°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

Both fish can tolerate a pH between 7 and 7.6. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 9–10 dGH. Regular testing will ensure conditions stay within this range.

To house Boeseman's Rainbowfish and Cairns Rainbowfish together, plan for an aquarium of at least 200 litres with a minimum length of 120 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: Plants - lighly covered, Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Leaf Litter/Blackwater. Meeting these requirements will help both species thrive.

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