Freshwater Shark (Wallago)

The Freshwater Shark (Wallago), scientifically known as Wallago attu, belongs to the Catfish family group. Adults reach a maximum size of approximately 150 cm and have a fusiform body shape with a fast growth rate. Classified as highly aggressive, this species primarily occupies the mid-level and bottom zones of the aquarium and produces a extreme level of biological waste.

To thrive, the Freshwater Shark (Wallago) requires a freshwater only aquarium with a minimum volume of 5500 litres and a tank length of at least 300 cm. Water temperature should be maintained between 19°C and 29°C, with a pH range of 6–7.6 and a general hardness of 1–20 dGH. A moderate water flow is preferred.

Due to its specialist needs, the Freshwater Shark (Wallago) is best suited for fishkeepers who can provide a carefully planned setup. This species is available in 2 varieties: Standard / Adult and Juvenile (Grow-out). Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.

When setting up an aquarium for the Freshwater Shark (Wallago), a moderate water flow best suits their natural preferences. Because this species occupies the mid-level and bottom zones, the aquarium layout should prioritise open swimming space in the centre of the tank for free movement and sufficient floor space with hiding spots among rocks, wood, or dense planting. Useful additions include a sand substrate to accommodate their sifting behaviour and smooth gravel or rounded substrate to protect their sensitive barbels. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.

Classified as highly aggressive, the Freshwater Shark (Wallago) is best housed alone, as they do not tolerate others of their kind in confined spaces. When choosing tankmates, any fish small enough to fit in its mouth will likely be eaten, conspecific aggression can be intense, especially in smaller tanks, and their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the mid-level and bottom zones can help reduce competition and territorial overlap.

Freshwater Shark (Wallago) is best for a fishkeeper who expects a species with attitude and plans the tank around that behavior and can provide someone who understands its individual space requirements. It makes the most sense for a hobbyist who will actually build around its needs, especially sand.

The most common mistake is treating Freshwater Shark (Wallago) like any other community fish and skipping the soft sand it needs to forage safely. Another frequent problem is forcing it into an over-busy community when it would do better with more room or more deliberate tankmate choices.