Can Bulolo Rainbowfish and Lyretail Killifish Live Together?

Bulolo Rainbowfish is a peaceful species (2/10), while Lyretail Killifish is generally mild-mannered (3/10). This modest difference means Lyretail Killifish may occasionally assert dominance over Bulolo Rainbowfish.

Bulolo Rainbowfish and Lyretail Killifish both frequent the Middle (Open Water) and Top (Surface) 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.

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

The safe temperature window for both species falls between 22°C and 26°C. Aim for the midpoint of this range (around 24.0°C) for optimal comfort.

The pH requirements of Bulolo Rainbowfish (7.5–8.8) and Lyretail Killifish (5.5–7) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 8–10 dGH. Regular testing will ensure conditions stay within this range.

To house Bulolo Rainbowfish and Lyretail Killifish 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, Plants - Floating, Leaf Litter/Blackwater. Meeting these requirements will help both species thrive.

Bulolo Rainbowfish prefers High (River/Stream) flow while Lyretail Killifish needs Low (Still Water) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

Bulolo Rainbowfish and Lyretail Killifish 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.