Can Black Ghost Knifefish and Malawi Eyebiter Live Together?

Black Ghost Knifefish is a moderately assertive species (6/10), while Malawi Eyebiter is semi-aggressive (8/10). This modest difference means Malawi Eyebiter may occasionally assert dominance over Black Ghost Knifefish.

Black Ghost Knifefish 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.

There is a critical concern: the Shy / Slow Moving (Easily Stressed) behaviour of one fish directly conflicts with the Eye Biter (Attacks slow moving fish) trait of the other — eye biters attack slow-moving fish, risking permanent injury..

Additional behavioural considerations to keep in mind: Aggressive fish may bully and stress shy, slow-moving species.

Worth noting: Black Ghost Knifefish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Malawi Eyebiter 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.

Both fish can tolerate a pH between 7.8 and 8. Maintaining a stable value within this band is more important than hitting an exact number.

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

To house Black Ghost Knifefish and Malawi Eyebiter together, plan for an aquarium of at least 475 litres with a minimum length of 150 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.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Black Ghost Knifefish 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.