Can Chili Rasbora and Flowerhorn Cichlid Live Together?

Chili Rasbora is a peaceful species (0/10), while Flowerhorn Cichlid is highly aggressive (10/10). This notable difference means Flowerhorn Cichlid may occasionally assert dominance over Chili Rasbora.

Large aggression gap (10 points) between Chili Rasbora and Flowerhorn Cichlid increases stress risk for the more peaceful fish.

Chili Rasbora and Flowerhorn Cichlid both frequent the 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.

There is a critical concern: the Nano / Bite-sized (Predation Risk) behaviour of one fish directly conflicts with the Piscivore (Eats small/nano fish) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Additional behavioural considerations to keep in mind: Aggressive fish may bully and stress shy, slow-moving species.

The safe temperature window for both species falls between 26°C and 28°C. Aim for the midpoint of this range (around 27.0°C) for optimal comfort.

The pH requirements of Chili Rasbora (4–7) and Flowerhorn Cichlid (7.4–8) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 9–10 dGH. Regular testing will ensure conditions stay within this range. An aquarium test kit is recommended for monitoring.

To house Chili Rasbora and Flowerhorn Cichlid together, plan for an aquarium of at least 336 litres with a minimum length of 120 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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: Plants - Densely covered, Plants - Floating, Leaf Litter/Blackwater, Sand (Sifters), Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Flowerhorn Cichlid is a plant destroyer, which conflicts with Chili Rasbora's requirement for live plants. Compromise where possible or prioritise the more critical need.

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