Can Cairns Rainbowfish and Tanganyikan Clown Cichlid (Eretmodus) Live Together?

Cairns Rainbowfish is a peaceful species (2/10), while Tanganyikan Clown Cichlid (Eretmodus) is semi-aggressive (7/10). This notable difference means Tanganyikan Clown Cichlid (Eretmodus) may occasionally assert dominance over Cairns Rainbowfish.

In terms of spatial distribution, Cairns Rainbowfish prefers the Middle (Open Water) and Top (Surface) zones, whereas Tanganyikan Clown Cichlid (Eretmodus) occupies the Bottom (Substrate) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

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

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.

The pH requirements of Cairns Rainbowfish (6.5–7.6) and Tanganyikan Clown Cichlid (Eretmodus) (8–9.5) do not overlap, making it impossible to satisfy both species simultaneously.

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

To house Cairns Rainbowfish and Tanganyikan Clown Cichlid (Eretmodus) together, plan for an aquarium of at least 110 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.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Leaf Litter/Blackwater, Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

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

Cairns Rainbowfish and Tanganyikan Clown Cichlid (Eretmodus) are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.