Can Black Pacu and Malawi Eyebiter Live Together?

Black Pacu is a generally mild-mannered species (4/10), while Malawi Eyebiter is semi-aggressive (8/10). This notable difference means Malawi Eyebiter may occasionally assert dominance over Black Pacu.

Black Pacu and Malawi Eyebiter 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: Black Pacu is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 23°C and 28°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

The pH requirements of Black Pacu (6–7.5) and Malawi Eyebiter (7.8–8.6) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 10–15 dGH. Regular testing will ensure conditions stay within this range.

To house Black Pacu and Malawi Eyebiter together, plan for an aquarium of at least 3800 litres with a minimum length of 300 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: Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Sand (Sifters), Plants - Densely covered. Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Black Pacu is a plant destroyer, which conflicts with Malawi Eyebiter'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.

Black Pacu and Malawi Eyebiter 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.