Can Red Top Cobalt Cichlid and Redline Rasbora Live Together?

Red Top Cobalt Cichlid is a semi-aggressive species (7/10), while Redline Rasbora is peaceful (1/10). This notable difference means Red Top Cobalt Cichlid may occasionally assert dominance over Redline Rasbora.

Large aggression gap (6 points) between Red Top Cobalt Cichlid and Redline Rasbora increases stress risk for the more peaceful fish.

Red Top Cobalt Cichlid and Redline Rasbora 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: Aggressive fish may bully and stress shy, slow-moving species. Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: Redline Rasbora is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 24°C and 27°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

The pH requirements of Red Top Cobalt Cichlid (7.5–8.5) and Redline Rasbora (4–6.8) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Red Top Cobalt Cichlid needs 10–25 dGH while Redline Rasbora requires 1–8 dGH.

To house Red Top Cobalt Cichlid and Redline Rasbora together, plan for an aquarium of at least 208 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.

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: Sand (Sifters), Established Algae (Otocinclus), Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.

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

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

Red Top Cobalt Cichlid and Redline Rasbora 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.