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In 2005, Thai fishermen caught a ~646-pound, 9-foot Mekong giant catfish, among the largest freshwater fish ever reliably recorded.

The fish died before release and was used as food, reflecting local customs.

Mekong giant catfish grow extremely fast and can reach roughly 330 to 440 pounds in about six years, while exceptional individuals can exceed 600 pounds.

Overfishing, dams, habitat loss, pollution, and climate change threaten this critically endangered species.

The Mekong River hides some of the largest freshwater fish on Earth, and in 2005, village fishermen in northern Thailand hauled in a Mekong giant catfish so massive that scientists compared it to a grizzly bear. That catch revealed how huge these fish can grow, how people use them, and why their future now looks uncertain.

The record fish surfaced near Hat Khrai, a village on the Mekong close to Thailand’s border with Laos. It required several people to bring the enormous catfish ashore. Once they dragged it ashore, Thai officials weighed the catfish at about 646 pounds and measured it at roughly 9 feet long. At the time, conservation groups and record‑keeping organizations treated it as the heaviest (though not necessarily the longest) Mekong giant catfish, and among the largest strictly freshwater fish that has been reliably documented. See a picture of this monster here.

A view of the Mekong River in Laos

©Mike Towers/Shutterstock.com

Village fishermen caught the fish and brought it ashore with help from others nearby. After news of this massive fish spread, fisheries staff and conservationists planned to keep the fish alive and move it for release so it could spawn. Officials had hoped the fish could be released, but it died before it could be returned to the river. Following local custom, villagers butchered the carcass and sold the meat, turning the rare catch into food for the community.

Mekong giant catfish rank among the world’s largest freshwater fish, but most never reach the size of the 2005 record. In healthy conditions, adults can grow to around 10 feet long and more than 600 pounds, though such giants are now extremely rare. Many large individuals weigh between 330 and 440 pounds, already dwarfing most river fish. These fish have smooth, pale bodies, broad heads, and powerful tails. Despite their massive size, adult Mekong giant catfish are not known as predatory fish; they lose their teeth as they mature and feed mainly on algae, detritus, and other plant material.

This is a “small” Mekong giant catfish.

©Jijiladouceur, CC BY 4.0 , via Wikimedia Commons – Original / License

People along the Mekong have eaten giant catfish for generations. They reportedly have mild, firm flesh. Meat from a very large specimen can carry cultural value, and sharing it at feasts strengthens community ties. As of 2026, however, scientists classify Mekong giant catfish as critically endangered and strongly discourage eating wild individuals. Overfishing, dams and other migration barriers, habitat degradation, and pollution are among the main threats to this rare species. Governments and conservation groups now use protected zones, fishing bans, and captive‑breeding programs to keep these river giants from disappearing entirely.

The bear‑sized catfish from 2005 shows how incredible life in the Mekong once was and might still be if we protect it. Its story blends everyday village fishing with record‑breaking science and a warning about the limits of a stressed river system. By respecting harvest rules, supporting habitat protection, and valuing living fish more than a single meal, people give Mekong giant catfish a chance to survive. If that happens, future generations may see more river monsters that match the legends instead of only reading about one long‑ago catch.

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