Can Chili Rasbora and Christmas Fulu Live Together?

Chili Rasbora is a peaceful species (0/10), while Christmas Fulu is moderately assertive (6/10). This notable difference means Christmas Fulu may occasionally assert dominance over Chili Rasbora.

Large aggression gap (6 points) between Chili Rasbora and Christmas Fulu increases stress risk for the more peaceful fish.

Chili Rasbora and Christmas Fulu 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.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

The safe temperature window for both species falls between 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

The pH requirements of Chili Rasbora (4–7) and Christmas Fulu (7.5–8.6) 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 Chili Rasbora and Christmas Fulu together, plan for an aquarium of at least 150 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: Plants - Densely covered, Plants - Floating, Leaf Litter/Blackwater, Sand (Sifters), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

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

Chili Rasbora and Christmas Fulu 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.