Wallago attu – The giant sheatfish

Wallago attu is the only freshwater catfish in the genus Wallago (sheatfish) of the family Siluridae, native to South and Southeast Asia. It’s commonly known as wallago catfish or giant sheatfish. Wallago attu is often mistaken for Wallagonia leerii (helicopter catfish), which is much larger in size. Lately, it was found that Wallago and Wallagonia are not particularly closely related within the family of Siluridae. In Vietnam, it’s called cá leo, which literally means “climbing fish” because it used to climb into farmers’ rice paddies.

• Scientific name: Wallago attu (Bloch and Schneider, 1801)
• Family: Siluridae (Sheatfishes)
• English: Giant sheatfish, wallago catfish
• Vietnamese name: Cá leo

Distribution

This freshwater species is widespread, occurring all across India, Pakistan, Sri Lanka, Nepal, Bangladesh, Myanmar, Laos, Thailand, Vietnam, Cambodia and Java in Indonesia. It is found in deep, slow-flowing large rivers and in lakes with a mud or silt substrate. It readily adapts to impoundments.

In Vietnam, Wallago attu is distributed in many different areas, most of which are along Tiền River and Hậu River (two forks of Mekong River when it enters Vietnam). Especially, some areas near the Vietnam-Cambodia border such as Châu Đốc, Tịnh Biên, Tân Châu (An Giang province) were once famous for catching the fish. It also occurs in the waters of some rivers and lakes in Vietnam’s Central Highlands like Sêrêpôk River or Krông Ana River.

Life Cycle

The species is a nocturnal predator which only undertakes short longitudinal migrations to the nearest stream, as well as some localized movements to pursue schools of smaller fish on which it preys. During the flood season it stays in swamps, canals and streams on the flood plain, where it also spawns. When the water level in the Mekong mainstream drops and the floodwater recedes, Wallago attu migrates to the Mekong River or larger tributaries, where it lives in deep pools until the next inundation period.

Fisheries and Aquaculture

The species is important in fisheries throughout its range and is a high-value fish, particularly in Vietnam and Cambodia, where it is mainly caught with hook and line, but also with gillnets. It is a very good gamefish species. Most giant wallago catfish found in Vietnamese restaurants are imported from Cambodia.

In Vietnam, there are very few wild wallago catfish in the Mekong River basin, and the species is classified as a rare fish that needs to be conserved. Fortunately, this precious fish has been successfully bred at the An Giang Aquaculture Breeding Center. Now the fish is farmed as a commercial fish in ponds and raft cages.

Culinary uses

The meat of the giant sheatfish is firm, delicious, sweet, fatty and boneless, so home cooks can cook it into many unique delicious dishes such as fresh fried wallago catfish, fried salted wallago catfish, braised wallago catfish with ginger or galanga leaves, grilled wallago catfish, wallago catfish sour soup… However, the most delicious and nutritious dish that the human body can easily absorb is the wallago catfish congee, which someone consider as an aphrodisiac food.