Can Brilliant Rummy-Nose Tetra and Cobalt Blue Zebra Live Together?

Brilliant Rummy-Nose Tetra is a peaceful species (1/10), while Cobalt Blue Zebra is semi-aggressive (8/10). This notable difference means Cobalt Blue Zebra may occasionally assert dominance over Brilliant Rummy-Nose Tetra.

Large aggression gap (7 points) between Brilliant Rummy-Nose Tetra and Cobalt Blue Zebra increases stress risk for the more peaceful fish.

Brilliant Rummy-Nose Tetra and Cobalt Blue Zebra both frequent the Middle (Open Water) and Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

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 Brilliant Rummy-Nose Tetra (5–7) and Cobalt Blue Zebra (7.8–8.6) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Brilliant Rummy-Nose Tetra needs 1–8 dGH while Cobalt Blue Zebra requires 10–25 dGH.

To house Brilliant Rummy-Nose Tetra and Cobalt Blue Zebra together, plan for an aquarium of at least 200 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: Plants - Densely covered, Leaf Litter/Blackwater, Sand (Sifters). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Cobalt Blue Zebra is a plant destroyer, which conflicts with Brilliant Rummy-Nose Tetra'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.

Brilliant Rummy-Nose Tetra and Cobalt Blue Zebra 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.