Can Cairns Rainbowfish and Emerald Green Cory Live Together?

Cairns Rainbowfish is a peaceful species (2/10), while Emerald Green Cory is peaceful (0/10). This modest difference means Cairns Rainbowfish may occasionally assert dominance over Emerald Green Cory.

In terms of spatial distribution, Cairns Rainbowfish prefers the Middle (Open Water) and Top (Surface) zones, whereas Emerald Green Cory 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 22°C and 26°C. Aim for the midpoint of this range (around 24.0°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 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 2–10 dGH. Regular testing will ensure conditions stay within this range.

To house Cairns Rainbowfish and Emerald Green Cory 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, Sand (Sifters). 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.