Mekong giant catfish (Pangasianodon gigas)

Description and biology

This catfish has a broad, flattened head and a smooth, scaleless body with a pale to grayish color. It lacks the bony plates found on some other catfish and has an upward-facing mouth adapted for feeding in the water column. Individuals can grow to very large sizes—commonly exceeding a metre in length and sometimes reaching much larger dimensions—though exact maximums vary among sources. It is primarily herbivorous as an adult, feeding on plant material and algae, while juveniles may eat more varied items.

Distribution and habitat

The species is endemic to the lower reaches of the Mekong River and associated floodplain lakes and tributaries, most notably Tonlé Sap and parts of the Mekong in Cambodia and southern Laos. Historical records indicate a wider distribution along the Mekong, but recent observations show populations are now fragmented. It is uncertain whether remaining fish in the Tonlé Sap system and other localized sites represent a single interbreeding population or several isolated groups. For information on the river system see Mekong River resources.

Threats and conservation

The Mekong giant catfish is classified as critically endangered by international conservation assessments. Major pressures include overfishing, loss and alteration of migratory routes due to dams and infrastructure, habitat degradation from agriculture and pollution, and reduced water quality and flow. Fishing pressure, both targeted and bycatch, has been a significant factor in population decline; more on fishing threats can be found at fishing impact references. Conservation efforts encompass legal protection, population monitoring, habitat protection and attempts to maintain or restore migration pathways.

Human use, aquaculture and cultural importance

The species has been valued as a food fish and is sometimes caught for local consumption and trade. Because wild numbers are so low, limited aquaculture programs have been developed to farm the species or closely related pangasiid catfish in captivity; see aquaculture practices. In some communities the fish carries cultural and symbolic significance, and its decline has prompted public interest in conservation and sustainable river management.

Notable facts and related species

The Mekong giant catfish is closely related to other members of the Pangasiidae family, such as the commercially farmed Iridescent shark (Pangasius hypophthalmus), which is often marketed under the general name pangasius or shark catfish. For comparisons with similar species consult related species information. Because of its size, migratory habits and sensitivity to river changes, the species is often cited as an indicator of the health of large tropical river systems. Ongoing conservation work emphasizes catch limits, protected areas, and efforts to mitigate the effects of dams and water management on migration and spawning.