Heavy rains have caused waste water from overflowing sewers across Ho Chi Minh City to leak into the newly-revived Nhieu Loc-Thi Nghe Canal, forcing thousands of fish to bustle up on the surface and gasp for air.
“It was pollution that forced them to the surface,” Tran Van Son of the city's aquatic life protection agency said of the unusual sight that has shocked many city dwellers the past few days.
Son blamed the situation on sewers connected to the upstream section of the canal, which runs through seven districts in the city.
“Heavy rains carried waste water with poisonous chemicals from sewers into the canal,” he said.
The canal has its own water treatment facilities, but they are inadequate when there is a large amount of water that needs to be treated, he said.
Son said it was not the first time that pollution had affected the fish, but it was clearly "the most serious."
He said many people have tried to catch the fish after spotting them on the surface. He urged local authorities to stop them.
Experts have warned many times that fish from the canal may contain poisonous substances due to the polluted water
The Nhieu Loc-Thi Nghe runs roughly eight kilometers. The city spent around a decade and more than US$390 million, including funding from the World Bank, to bring it back from a stinky, dirty canal several years ago.