How big is the Mekong giant catfish?
The Mekong giant catfish, Pangasianodon gigas, lives only in the Mekong basin[1]. It can reach 3 meters (about 10 feet), and weights of 350 kilograms (770 pounds) have been reported[1]. It is one of the fastest-growing fish in the world: 150 to 200 kilograms (330 to 440 pounds) in six years[1].
The largest specimen weighed in Thailand since records began in 1981 was a female 2.7 meters long and 293 kilograms (646 pounds), caught in 2005[2]. For seventeen years it stood as the largest freshwater fish ever recorded. The record fell in June 2022 in Cambodia, to a giant freshwater stingray of nearly 300 kilograms, caught and released south of Stung Treng[5].
Photo by Jijiladouceur on Wikimedia Commons · CC BY 4.0
A toothless giant that eats algae
Despite its size, the giant catfish is not a predator. Young fish have teeth and barbels, which they lose by the time they reach 30 to 50 centimeters (1 to 1.6 feet)[1]. Adults graze on algae and plants on the riverbed[1].
Photo by KKPCW on Wikimedia Commons · CC BY-SA 4.0
Where does the Mekong giant catfish live?
Much of its life cycle is still unknown[1]. It is thought to grow up mainly in the Mekong and Cambodia's Tonle Sap Lake, then swim hundreds of miles upstream at the start of the rainy season to spawn, as far as Thailand[2].
It has not vanished from Cambodia. In December 2024, six giant catfish were caught by accident and released within five days on the Tonle Sap and the Mekong, including two over 2 meters long weighing 120 and 131 kilograms: the most ever recorded in such a short time[3]. Another, weighing 63 kilograms, was returned to the river in Kampong Cham province in January 2026[4].
Why the Mekong giant catfish is critically endangered
The species is listed as critically endangered on the IUCN Red List, and international trade is banned under CITES[1]. Its population is estimated to have fallen by about 80% over recent decades[3]. In Thailand, catches dropped from 11 fish in 2000 to 7 in 2001 and 5 in 2002[2].
Overfishing is the first cause cited[1]. Dams also weigh on migratory fish: according to a study quoted by the WWF, dams in the basin could cut fish catches by 23 to 39%[6]. The giant catfish is one of 18 Mekong fish species listed as critically endangered[6].
Fishing bans, captive breeding and releases
Fishing for it is banned in Thailand, Laos and Cambodia, but the bans are poorly enforced[2]. In 2006, nearly sixty Thai fishers pledged to stop catching it[2]. Thailand's Department of Fisheries breeds it in captivity: between 2000 and 2003, about 10,000 captive-bred fish were released[2].
In Cambodia, the Fisheries Administration, fishing communities and the Wonders of the Mekong research project recover fish caught by accident and release them[3]. Each catch sheds light on a species whose movements are still poorly understood.
Sources
- FishBase, “Pangasianodon gigas” species summary, citing the IUCN Red List (assessed April 13, 2011): size, weight, growth, diet, status , accessed October 8, 2026
- Wikipedia, “Mekong giant catfish,” revision of July 5, 2026 (secondary source citing the IUCN and press): 2005 record, catches in Thailand, breeding program, 2006 fishers' pledge, migration , accessed October 8, 2026
- AP, via Khaosod English, “Huge and rare Mekong catfish spotted in Cambodia, raising conservation hopes” , December 13, 2024
- FISHBIO, “Rare giant Mekong catfish released back into river in Kampong Cham” , January 2026
- Al Jazeera, “World's largest freshwater fish caught in Cambodia” , June 21, 2022
- Hughes, K. et al., WWF and 25 organizations, “The Mekong's Forgotten Fishes” , 2024
Pierre-Marie Coupry
Editor-in-chief of the French travel site Bon Plan Voyage, where he has published since 2012. He checks every practical detail against official sources and proofreads everything before it goes live.
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