One fifth of Mekong River’s tropical fish face extinction


A World Wildlife Fund report has revealed that 19% of the Mekong River’s fish are threatened with extinction.

Name Mekong’s Forgotten Fishes, the WWF joint report found that there are at least 1,148 fish species in the Mekong River, making it the world’s third most diverse river after the Congo and Amazon River systems, but that up to 1 in 5 species are already threatened with extinction, writes Jeremy Gay.

World’s largest inland fishery

The Mighty Mekong River is a record breaker, being home to the largest giant freshwater stingray (Urogymnus polylepis), the Mekong giant catfish (Pangasianodon gigas) and the giant barb (Catlocarpio siamensis). Every year it hosts one of the world’s largest freshwater fish migrations with an estimated 5 billion fish migrating, but those fish are caught and eaten by at least 40 million people, accounting for at least 15% of the entire global inland fish catch. The fishery has been valued at $11 billion, but the WWF report has found it just isn’t sustainable.

Habitat Loss

Fish numbers have declined massively, yet it isn’t just from overfishing. Other threats include habitat loss, hydroelectric dams preventing fish migration, conversion of wetlands for agriculture, sand mining, non native invasive species and climate change. Fish populations declined in Lake Tonle Sap by 88% between 2003 and 2019 according to the Mekong’s Forgotten Fishes Report. Cambodia’s Lake Tonle Sap belongs to the Mekong river system and is the largest freshwater lake in south east asia. It has one of the most diverse and productive ecosystems in the world and was designated as a Biosphere Reserve by UNESCO in 1997 due to its high biodiversity.

"The alarming decline in fish populations in the Mekong is an urgent wake-up call for action to save these extraordinary – and extraordinarily important – species, which underpin not only the region’s societies and economies but also the health of the Mekong’s freshwater ecosystems," said Lan Mercado, WWF Asia-Pacific Regional Director.

"These fishes have swum through our civilisations and cultures for millennia and millions of people still depend on them every day. But overlooked by decision makers, they are disappearing. We must act now to reverse this disastrous trend because the communities and countries of the Mekong cannot afford to lose them."

IUCN Red List of Threatened Species 

18 of the Mekong River’s fish species are already listed as Critically Endangered by the IUCN Red List of Threatened Species, but a further 38% (436 fish species,) are listed as 'data deficient' meaning that nobody knows their true numbers or how sharply they are in decline. But there is hope in the form of several conservation programs including the Freshwater Challenge – the largest freshwater restoration and protection initiative in history, and the Emergency Recovery Plan for Freshwater Biodiversity.

"The good news is that it’s not too late to restore the Mekong and bring its fishes back from the brink,” Zeb Hogan told WWF. Hogan is Lead for Wonders of the Mekong, which funded the report and presents the Monster Fish show on Nat Geo Wild. "By factoring the future of fishes and fisheries into decisions that impact the basin while building on the expertise, knowledge and solutions of local communities, we can chart a new course for the Mekong – securing food and jobs for millions, safeguarding cultural icons, boosting biodiversity and enhancing resilience to climate change."

Notable Freshwater fish of the Mekong River

Species from the Mekong that aquarists will be familiar with include:

Sultan fish, Leptobarbrus rubipinna
Giant gourami, Osphronemus goramy
Giant snakehead, Channa micropeltes
Long snouted pipefish, Doryichthys boaja
Mekong croaking gourami, Trichopsis schalleri
Jullien’s golden carp, Probarbus jullieni
Asian arowana, Scleropages formosus
Mekong fighting fish, Betta smaragdina
Hillstream loach, Sewellia breviventralis