Can Asian Upside Down Catfish and Freshwater Shark (Wallago) Live Together?

Asian Upside Down Catfish is a semi-aggressive species (8/10), while Freshwater Shark (Wallago) is highly aggressive (10/10). This modest difference means Freshwater Shark (Wallago) may occasionally assert dominance over Asian Upside Down Catfish.

Both Asian Upside Down Catfish and Freshwater Shark (Wallago) are highly aggressive, increasing the risk of violent confrontations.

Asian Upside Down Catfish and Freshwater Shark (Wallago) both frequent the Middle (Open Water) and Bottom (Substrate) 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: Two aggressive species housed together increases risk of fighting.

Worth noting: Asian Upside Down Catfish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Freshwater Shark (Wallago) is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Asian Upside Down Catfish and Freshwater Shark (Wallago) to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations. A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

The safe temperature window for both species falls between 23°C and 27°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 6 and 7.6. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–20 dGH. Regular testing will ensure conditions stay within this range.

To house Asian Upside Down Catfish and Freshwater Shark (Wallago) together, plan for an aquarium of at least 5500 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.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels), Sand (Sifters). 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.