The Mekong River basin has a level of fish biodiversity that is rivaled only by the Amazon River basin.

 rel= © Adam Cathro


Ms Trang Dangthuy
Mekong River Ecoregion Coordinator

From the Mekong’s turbulent headwaters to its placid delta and confluence with the sea, its metamorphosis through each season – dry, hot, and wet – the river’s natural evolution is symbolic of change.

Today, this change is mirrored in the region’s aspirations for a better life, the likes of which are shaping the future of the Mekong and that of its people.

Everyday life for the people of the Mekong basin is entwined with the natural rhythm of the river. Its active floodplains and biodiversity rich fisheries support food security and livelihoods. Its calm waters are used in recreation and for transportation. It replenishes crops, livestock and households, and for centuries, has brought meaning to an array of cultures.

Weaving 4,800 km from its icy headwaters on the Tibetan Plateau, the river flows through steep canyons of China (the upper basin), through Myanmar, Laos, Thailand, Cambodia and Vietnam (the lower basin), fanning out across the tropical lowlands of the Mekong Delta then draining into the South China Sea.

Today, the lower Mekong River mainstream remains free-flowing, unlike so many of the world's other great rivers. The people of the Greater Mekong have a unique opportunity to become a model of sustainable development, improving living standards through conservation of this vast natural resources and the ecosystem services it provides.

An abundance of life

The Mekong, its floodplains and tributaries support huge collections of unique flora and fauna including, critically endangered freshwater Irrawaddy dolphins, the world’s largest freshwater fish – the Giant freshwater stingray - giant turtles, Mekong giant catfish, waterbirds, and Siamese crocodiles.

River of giants

The Mekong is one of the last large rivers in the world that still has active natural floodplain that nurtures an extremely high numbers of fish species, including some of the world’s largest.

With over 1,300 species of fish, the Mekong River is the world’s most productive inland fishery. Providing livelihoods to 60 million people, this fishery accounts for up to 25% of the global inland catch, providing up to 80% of all animal protein in to the people of the Mekong River basin. Fisheries in the Mekong River are worth 2.5 billion USD per year to the countries of the Mekong.

Many of the species in the Mekong are endemic. Many are super-sized. Among the species of the Mekong are some of the world's most charismatic fish including four to the world's largest:

  • Giant freshwater stingray Himantura chaophraya (up to 600kg)
  • Mekong giant catfish Pangasianodon gigas (up to 350kg)
  • Giant pangasius Catlocarpio siamensis (up to 300kg)

Endangered species

Beyond fish, the Mekong basin is also home to a tremendous diversity of endangered species such as:

  • Irrawaddy dolphin Orcaella brevirostris
  • the Giant Ibis Pseudibis gigantea
  • Siamese crocodile Crocodylus siamensis


"Today, the lower Mekong River mainstream remains wild and free-flowing, unlike so many other great rivers of the world. Maintaining its health is one of the region's best defences against the impacts of climate change. "


Sampans meet at early morning market in the Mekong Delta where rivers converge Vietnam

© Elizbeth Kemf / WWF

River of Giants

The critically endangered Mekong giant catfish. © WWF
Wild populations of the iconic Mekong giant catfish will be driven to extinction if hydropower dams planned for the Mekong River go ahead, says a new report by WWF.

The report, River of Giants: Giant Fish of the Mekong, profiles four giant fish living in the Mekong that rank within the top 10 largest freshwater fish on the planet. At half the length of a bus and weighing up to 600kgs, the Mekong River’s Giant freshwater stingray is the world’s largest freshwater fish. The critically endangered and culturally fabled Mekong giant catfish ranks third at up to 3 metres in length and 350kgs.

Mekong dolphins on the brink

The critically endangered Irrawaddy dolphin, Orcaella brevirostris, photographed at Kratie Province in northeast Cambodia. The Mekong dolphin population is estimated at between 66 and 86 individuals inhabiting a 190km stretch of the Mekong River between Cambodia and Lao PDR. © WWF
This mortality report by WWF says the Mekong dolphin’s are on the verge of extinction. Since 2003, at least 104 dolphins have died. This is an average of one dolphin death a month. This rate of mortality cannot be sustained.

Dolphins and dams don't mix

Irrawaddy dolphins (Orcaella Brevirostris) at Koh Kon Sat, Mekong River, Cambodia. The dolphins were photographed during the dolphin population research conducted by WWF Cambodia's Mekong Dolphin Conservation Project in November 2007. © WWF
This comprehensive reports spells out the serious risks posed by the proposed Don Sahong dam to the Mekong Irrawaddy dolphin population in southern Laos.

The Case of That Luang Marsh

That Luang Marsh, Vientiane Capital, Lao PDR. © WWF
Learn about the value of largest wetland in Vientiane, the capital city of Laos, to it's people and the city.