Can Pink Tailed Chalceus and Rachov's Killifish (Annual) Live Together?

Pink Tailed Chalceus is a moderately assertive species (6/10), while Rachov's Killifish (Annual) is generally mild-mannered (3/10). This modest difference means Pink Tailed Chalceus may occasionally assert dominance over Rachov's Killifish (Annual).

In terms of spatial distribution, Pink Tailed Chalceus prefers the Top (Surface) zone, whereas Rachov's Killifish (Annual) occupies the Middle (Open Water) and Bottom (Substrate) zones. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

There is a critical concern: the Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Additional behavioural considerations to keep in mind: Shrimp eaters may also prey on very small nano fish.

Worth noting: Pink Tailed Chalceus is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 23°C and 26°C. Aim for the midpoint of this range (around 24.5°C) for optimal comfort.

Both fish can tolerate a pH between 6 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–12 dGH. Regular testing will ensure conditions stay within this range.

To house Pink Tailed Chalceus and Rachov's Killifish (Annual) together, plan for an aquarium of at least 250 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: Driftwood (Digestion/Hiding), Plants - Floating, Soil / Nutrient Rich, Leaf Litter/Blackwater, Plants - Densely covered. Meeting these requirements will help both species thrive.

Pink Tailed Chalceus prefers High (River/Stream) flow while Rachov's Killifish (Annual) needs Low (Still Water) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

Pink Tailed Chalceus and Rachov's Killifish (Annual) 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.

Feeding time deserves special attention with this pairing. Pink Tailed Chalceus is a known shrimp eater and may prey on small invertebrates or nano fish like Rachov's Killifish (Annual).