Study finds a giant fish thought extinct spotted in Mekong River

WASHINGTON, D.C.: A huge fish thought to be extinct has been spotted three times in recent years in the Mekong River.

Chheana Chhut, a researcher at the Inland Fisheries Research and Development Institute in Phnom Penh, Cambodia said the predatory fish can grow up to 4 feet in length and has a conspicuous knob at the tip of its lower jaw. A striking patch of yellow surrounds its large eyes.

With the last confirmed sighting in 2005, "this species of fish seems to have disappeared from the Mekong region for decades," said Chheana, who is a co-author of a study published online this week in the journal Biological Conservation that documents the recent sightings.

Since 2017, biologists tracking migratory fish species in Cambodia have developed relationships with local fishing communities, asking them to alert any unusual sightings.

That's how researchers became aware of the three giant salmon carp found in the Mekong River and a tributary in Cambodia between 2020 and 2023.

Researchers say the sightings give them new hope for the species' fate. One nickname for the species is "ghost fish."

But the fish's plight also spotlights the perils facing all migratory species in the Mekong, which is impacted by industrial pollution and overfishing.

More than 700 dams are built along the river and its tributaries, and there are very few functional "fish passages" to help species navigate obstructions, said Brian Eyler, director of the Southeast Asia Program at the Stimson Center in Washington, who was not involved in the research.

The biologists said they hope that working with local communities in Thailand and Laos will enable them to confirm if the fish still swim in other stretches of the Mekong River.