Catfish, with their distinctive whiskered faces, are a diverse group found in freshwater environments globally. Some species attain immense sizes, leading to interest in identifying the largest contenders. These aquatic giants highlight the incredible scale to which freshwater fish can grow.
The Contenders for “Biggest”
Several species vie for the title of the world’s biggest catfish. The Mekong Giant Catfish, found in Southeast Asia, is one of the most recognized contenders. This species, a member of the shark catfish family, is known for its grey to white coloration and lacks teeth and barbels as adults.
Another contender is the Wels Catfish, found across Europe and parts of Asia. This scaleless fish has an elongated body, often mottled brown or grey-black. It is recognized as one of Europe’s largest freshwater fish. In South America, the Piraíba, also known as the Goliath Catfish or Lau-Lau, is a large species. It has a bulky, silvery-grey body with a white belly and distinct long barbels.
Record-Breaking Dimensions
The Mekong Giant Catfish holds a notable place in record books, recognized by Guinness World Records as the world’s largest freshwater fish in 2005. These fish can reach lengths of up to 3 meters (9.8 feet) and reportedly weigh up to 350 kilograms (770 pounds). A female caught in Thailand in 2005 measured 2.7 meters (8 feet 10 inches) and weighed 293 kilograms (646 pounds).
The Wels Catfish also reaches impressive dimensions, with authenticated specimens weighing nearly 135 kilograms (297.6 pounds). The longest Wels Catfish on record was an unweighed specimen from the Po River, measuring 2.85 meters (9.4 feet) in 2023. Some reports suggest Wels Catfish may potentially exceed 3 meters (9.8 feet) in length and over 200 kilograms (440 pounds), though such sizes are rare and historically less proven. The Piraíba, or Lau-Lau, is listed on the IGFA record books with specimens reaching 155 kilograms (341 pounds). This species can potentially grow up to 3.6 meters (11.8 feet) in length.
Where These Giants Reside
The Mekong Giant Catfish is endemic to the Mekong River basin in Southeast Asia, spanning Myanmar, Laos, Thailand, Cambodia, and Vietnam. These fish primarily inhabit the river’s main channels, often in depths greater than 10 meters (33 feet). They are migratory, traveling significant distances to spawn, and their habitat historically extended across nearly the entire 4,800 km length of the Mekong River system.
The Wels Catfish is native to river systems draining into the North, Baltic, Black, Caspian, and Aral Seas, encompassing central, southern, and eastern Europe, and parts of Western Asia. They prefer large, warm lakes and deep, slow-flowing rivers, often seeking shelter in riverbed holes or sunken trees. This species has also been introduced to various Western European countries, becoming well-established.
The Piraíba inhabits the Amazon and Orinoco River basins, and other tropical freshwater and brackish environments in South America. These migratory catfish prefer deeper, flowing channels and can also be found in brackish waters around river mouths, particularly during their juvenile stages.