Catfish (order Siluriformes) represent one of the most diverse groups of bony fish, inhabiting a wide range of aquatic environments across the globe. These fish are instantly recognizable by the prominent sensory barbels, or “whiskers,” which surround their mouths, aiding in navigation and foraging. Catfish exhibit an astonishing variety in size, with some species measuring only a few centimeters while others grow into true riverine leviathans. Determining the largest specimen requires verifiable measurements of weight and length.
Identifying the Official Record Holder
The largest verifiable catfish ever officially recorded belongs to the species Pangasianodon gigas, known as the Mekong Giant Catfish. This colossal fish was captured in the Mekong River in northern Thailand in May 2005. The female specimen measured 2.7 meters (8 feet 10 inches) in length and registered a weight of 293 kilograms (646 pounds) when measured by local fisheries officials.
This catch holds a significant place in ichthyology, as it was recognized at the time as the largest entirely freshwater fish ever documented worldwide. The documentation highlights the challenges of verifying historical claims, which often lack precise measurements, against a modern, officially recorded catch. Following its capture, the fish was taken by Thai officials for a captive breeding program but unfortunately died in captivity.
The Contenders: Other Giant Species
While the Mekong Giant Catfish holds the official size record, two other species regularly grow to similarly formidable dimensions. The Piraíba, or Goliath Catfish (Brachyplatystoma filamentosum), is the largest catfish in South America, inhabiting the Amazon and Orinoco river basins. This species is known for its impressive length, capable of reaching an estimated 3.6 meters (12 feet).
Despite its potential length, the Piraíba’s maximum documented weight is significantly less than the Mekong record, with the IGFA All-Tackle record standing at 155 kilograms (341 pounds). The Wels Catfish (Silurus glanis) from Europe and Western Asia is another massive species, known to exceed 2.5 meters in length, with unverified reports claiming specimens of up to 3 meters.
The heaviest authenticated Wels Catfish weighed approximately 135 kilograms (297.6 pounds), less than half the weight of the record-holding Mekong fish. Although these two contenders may rival or exceed the Mekong Giant Catfish in maximum length, the sheer bulk of the Southeast Asian species secures its place as the heaviest recorded specimen.
Conservation Status of Giant Catfish
The Mekong Giant Catfish is classified as Critically Endangered by the International Union for Conservation of Nature (IUCN). These apex predators play a role in their river ecosystems, but their large size and migratory behavior make them especially vulnerable to human impact. The largest populations have declined by an estimated 80 to 90 percent over the past several decades.
The primary threats include intense overfishing, which often targets the largest, most reproductively mature fish, and extensive habitat degradation. The construction of large dams across river systems like the Mekong blocks the migration routes these fish rely on for spawning and feeding. The continued pressures on these massive species mean that any future record-breaking catches are likely to become even rarer events.