Can Brilliant Rummy-Nose Tetra and Molly (Sailfin/Black/Dalmatian) Live Together?

Brilliant Rummy-Nose Tetra is a peaceful species (1/10), while Molly (Sailfin/Black/Dalmatian) is generally mild-mannered (3/10). This modest difference means Molly (Sailfin/Black/Dalmatian) may occasionally assert dominance over Brilliant Rummy-Nose Tetra.

Brilliant Rummy-Nose Tetra and Molly (Sailfin/Black/Dalmatian) 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.

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 Molly (Sailfin/Black/Dalmatian) (7.5–8.5) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Brilliant Rummy-Nose Tetra needs 1–8 dGH while Molly (Sailfin/Black/Dalmatian) requires 12–30 dGH.

To house Brilliant Rummy-Nose Tetra and Molly (Sailfin/Black/Dalmatian) together, plan for an aquarium of at least 75 litres with a minimum length of 60 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, Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

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 Molly (Sailfin/Black/Dalmatian) 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.