While the weight of the fish in the photo is unknown, the species holds the world record as the largest freshwater fish ever caught, weighing in at 646 pounds (293 kilograms).
The Mekong giant catfish is listed as critically endangered by the World Conservation Union.
But a new dam project planned for Khone Falls threatens the migration of this so-called megafish, according to Zeb Hogan, who heads the National Geographic Society's Megafishes Project.
A fisher returns to shore with a Mekong giant catfish caught at Khone Falls in Laos last year.
The huge species is illegal to catch and is generally caught accidentally.
Today there may only be a few hundred adult giant catfish left in the entire Mekong River system.
The group of fishers who caught this giant catfish initially hoped to sell it. But when they could not find any buyers, they ended up distributing the meat among people in their village. A fisher at Khone Falls in Laos holds a large Bagarius catfish.
His basket trap, known as a Lop in the Lao language, is also used to catch fish such as the pa se ee, a carp native to the area.
Scientists say the Khone Falls area supports at least 201 fish species, including many endemic or endangered species. It also supports one of the few remaining concentrations of freshwater dolphins still living in the Mekong. A child poses with the head of a Mekong giant catfish caught at Khone Falls in Laos in August last year.
The giant catfish was once plentiful throughout the Mekong River system, but in the last century the population has declined 95 to 99 percent, according to Hogan of the Megafishes Project.
Last year only one giant catfish was caught at Khone Falls.
"Everyone heard about the catch, and hundreds of people showed up to look at it," said photographer Suthep Kritsanavarin.
A young boy uses a rope to drag himself across the raging Sahong
channel at Khone Falls in Laos.
The Sahong channel is the only channel in the area without a waterfall—and is the proposed site for a hydroelectric dam that environmentalists say will cut off a vital migratory fish route.
So far the Mekong remains almost untouched. Only China has dammed the main stream of the river at two locations. But there are now plans for a dozen dams to be built on the Mekong in China, Laos, and Thailand.
"The Mekong River is the most productive river on Earth," said Hogan of the Megafishes Project.
"The damming of the river could have devastating consequences for fisheries."
A man named Samnieng traverses Khone Falls in Laos holding a basket trap for catching fish.
Barefoot fishers use bamboo ladders to reach the middle of the falls to jam the trap between rocks to hold it in place.
"It takes a lot of skill, and it's very scary," said photographer Kritsanavarin.
"There have been tourists who have fallen into these waters and died."
Bamboo filter traps stand in the raging waters of the Sahong channel at Khone Falls in Laos.
The fishing contraptions force fish up angled bamboo ramps where they land at the fishers' feet.
"The way the fish is caught is totally in sync with the environment," said Hogan of the Megafishes Project.
"Water goes up and down according to the flood cycle, so the fishers have very specific, efficient, and elegant methods of fishing based on the season."
Conservationists warn that a proposed dam on the channel will devastate the fisheries there.