The world of catfish (order Siluriformes) is incredibly diverse, encompassing over 3,000 species that range from tiny aquarium dwellers to massive river giants. These fish are characterized by their prominent barbels, which resemble cat whiskers, and their lack of scales. While many species are large, the Mekong Giant Catfish (Pangasianodon gigas) consistently stands out as the undisputed champion of size.
The World’s Largest Catfish Species
The Mekong Giant Catfish is a freshwater fish recognized for its size and streamlined, shark-like appearance. This species holds the record for the largest documented entirely freshwater fish. The largest recorded specimen, caught in 2005, measured nearly 2.7 meters (8 feet 10 inches) in length and weighed 293 kilograms (646 pounds). Older, unverified reports suggest individuals may have reached up to 3 meters (9.8 feet) and weighed over 300 kilograms (660 pounds).
The adult fish possesses a gray to white coloration. It is notable for the near-total absence of barbels, or “whiskers,” which are a defining feature of most catfish species. Furthermore, the adult fish is toothless. This species is currently listed as Critically Endangered, with its population having plummeted by an estimated 90% in recent decades due to overfishing and habitat loss.
Where the Giant Catfish Lives
The Mekong Giant Catfish is endemic to the Mekong River basin in Southeast Asia, a vast waterway flowing through countries like Thailand, Laos, Cambodia, and Vietnam. Historically, its range extended across almost the entire length of the river. Today, the wild population is severely restricted, primarily found in the lower half of the Mekong mainstream.
The Mekong Giant Catfish is primarily a herbivore, feeding on algae and other plant life that it scrapes from the riverbed. This diet is unusual for a fish of its magnitude, which is often assumed to be a predator. The species is also known for its migratory behavior, traveling vast distances within the river system to reach specific spawning grounds. The construction of dams and other infrastructure projects along the Mekong River poses a significant threat by blocking these essential migration routes necessary for reproduction.
Other Catfish Species That Grow Massive
While the Mekong Giant Catfish is the largest, other species around the world also attain massive sizes. The Wels Catfish (Silurus glanis) is the largest freshwater fish in Europe and Western Asia. Authenticated records show specimens reaching 2.73 meters (8.9 feet) in length and weighing nearly 135 kilograms (297.6 pounds). Unverified historical accounts suggest the Wels Catfish may have reached lengths of 4.5 meters (15 feet) and weights of 300 kilograms (660 pounds), placing it in the same size class as the Mekong giant.
In South America, the Piraíba, or Goliath Catfish (Brachyplatystoma filamentosum), is the largest catfish species in the Amazon and Orinoco river basins. This migratory species can reach lengths of up to 3.6 meters (12 feet) and weights of 200 kilograms (440 pounds), though the largest recorded catch was 155 kilograms (342 pounds).
North America’s largest native catfish is the Blue Catfish (Ictalurus furcatus), found primarily in the Mississippi River basin. While typically smaller than its global counterparts, the Blue Catfish can still reach impressive sizes. The largest documented specimen weighed 64.9 kilograms (143 pounds) and measured 1.7 meters (65 inches) in length.