Why is Tonle Sap an important fishing ground?

The Tonle Sap is one of the world’s richest sources of freshwater fish due to a unique annual hydrological phenomenon involving the Mekong River.1

During the rainy season, the Mekong’s massive volume of water causes the Sab River to reverse its flow, pushing water into the lake and expanding its surface area significantly. This seasonal flooding creates a vast, nutrient-rich environment that supports a major carp-breeding and harvesting industry.21

The lake serves as a critical economic and nutritional hub, featuring numerous floating fishing villages. The fish harvested from these waters, often processed as fermented or salted products, serve as essential staples in the Cambodian diet. Because of its ecological significance, the lake was designated a World Network Biosphere Reserve by UNESCO in 1997.2