Photo by K on Pexels
Mekong nature, from dolphins to the Tonle Sap
The river's species and the cycles that shape it: Kratie's dolphins, the giant catfish, and the Tonle Sap reversing its flow twice a year.
Nature and wildlife: Mekong River stories
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Photo by K on Pexels
Nature and wildlifeWhy the Tonle Sap reverses its flow twice a year
From late May, the Mekong flood pushes up the Tonle Sap River and the largest lake in Southeast Asia grows six times larger. In the fall, the water flows back the other way.
Updated October 13, 2026 · 6 min
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Photo by Pierre André on Wikimedia Commons · CC BY-SA 4.0
Nature and wildlifeIrrawaddy dolphins: about a hundred in the Mekong, and a population on the rise
About a hundred dolphins still live in the Mekong, along a stretch of river of some 110 miles in Cambodia. Their numbers have been rising for a few years, but they have already disappeared from Laos.
Updated October 13, 2026 · 5 min
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Photo by Tambe on Wikimedia Commons · CC BY-SA 4.0
Nature and wildlifeThe Mekong giant catfish: 600 pounds, toothless and critically endangered
It can grow longer than 10 feet and heavier than 600 pounds, loses its teeth as it grows and feeds on algae. The Mekong giant catfish lives nowhere but the Mekong basin, where it is now critically endangered.
Updated October 13, 2026 · 5 min
Understanding the Mekong
Our reference pages on the Mekong: its length, its source, the countries it crosses, its floods.