Mass Fish Die-Off in Mao River; Poisoning Suspected
Hundreds of fish died in Chiang Mai's Mao River on August 17, with authorities suspecting concentrated toxins from upstream agricultural activities as the cause and warning residents not to consume them.
Chiang Mai – On August 17, numerous fish of various species were found floating dead throughout the Mao River in Pong Nam Ron subdistrict, Fang district, Chiang Mai province. Local residents rushed to collect the fish by the sackful for consumption and sale. Sithichai Pandee, a member of the Pong Nam Ron subdistrict administration representing Village 3, revealed that fish of all types showed signs of intoxication and were dying in large numbers, particularly in the areas around the weir at Ban Hua Fai and near Ban Mon Pin Nuea. Officials from Fang district, fisheries, village leaders, local water authority, and Fang police investigated and found the fish were in spawning condition with full roe, as the breeding season was approaching. These are local fish species that the community has been conserving. Upon examination, the gills of dead fish showed dark discoloration, leading to a preliminary assessment that the fish were exposed to concentrated toxins. Given agricultural and orange orchard activities upstream, authorities collected dead fish for further laboratory analysis. Mass fish die-offs in the Mao River have occurred before, most recently in 2566 (2023). After a two-year gap, fish populations had recovered and the ecosystem seemed stable, making this new die-off particularly unfortunate. Residents have called on authorities to identify and prosecute those responsible. The Pong Nam Ron subdistrict administration has issued public announcements warning residents not to consume or sell the fish, as they died under unnatural circumstances and may pose health risks to consumers.
