Can Rio Negro Dwarf Cichlid and Swordtail Live Together?

Rio Negro Dwarf Cichlid is a semi-aggressive species (7/10), while Swordtail is generally mild-mannered (4/10). This modest difference means Rio Negro Dwarf Cichlid may occasionally assert dominance over Swordtail.

Rio Negro Dwarf Cichlid and Swordtail 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.

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

The safe temperature window for both species falls between 22°C and 28°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

The pH requirements of Rio Negro Dwarf Cichlid (4–6.5) and Swordtail (7–8.3) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Rio Negro Dwarf Cichlid needs 0–5 dGH while Swordtail requires 12–30 dGH.

To house Rio Negro Dwarf Cichlid and Swordtail together, plan for an aquarium of at least 110 litres with a minimum length of 80 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: Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Sand (Sifters), Plants - Densely covered. 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.

Rio Negro Dwarf Cichlid and Swordtail 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.