Toxic gases and floating particles of unknown origin were suspected to have caused Tuesday’s fish deaths along a major canal in Ho Chi Minh City, as experts urge the completion of a wastewater treatment plant in the city aimed at improving water sanitation.

Dead fish were again found yesterday at intervals along a section of the Nhieu Loc-Thi Nghe Canal that runs through Phu Nhuan District.

With a total length of 8.7 kilometers, the canal snakes its way through five districts of Ho Chi Minh City, having received a facelift in 2012 as part of a series of actions taken by authorities to tackle worsening pollution in the waterway.

The water in the canal in Phu Nhuan was visibly murky, and thick bubbles could be seen at the surface along with toxic gases and sludge from the canal bed.

Plastic bags, water cartons, and plastic bottles were also seen floating on the canal’s surface despite constant collection efforts by sanitation workers.

Results of water quality monitoring revealed evidence of poor water quality, increased turbidity, and a decline in dissolved oxygen levels, according to Tran Dinh Vinh, manager at the Branch for Quality Control and Protection of Fishery Resources under the municipal Department of Agriculture and Rural Development.

Vinh said the accumulation of sludge and unprocessed litter from sewage systems at the canal bed was to blame for the observed surfacing of gas and mud.

Dr. Tran Huu Loc from Nong Lam (Agriculture-Forestry) University in the city said toxic gases like ammonia, methane, and hydrogen sulfide that had been spread along with the gas movement were among the causes of the fish deaths.

Loc added the problem could be dealt with by dredging the bed of the canal to get rid of the accumulated sludge.

Tons of fish were found dead in the same canal in May following a downpour that washed toxic gases into the canal.

In response to recent fish deaths in the Nhieu Loc-Thi Nghe canal, Vice Chairman of Ho Chi Minh City People’s Committee Le Thanh Liem urged the municipal Department of Transport to speed up the completion of a wastewater treatment plant in the city.

Liem added that the committee had also tasked the municipal inland waterways authority to carry out the dredging of the canal bed.

Sanitation workers collect dead fish in the Nhieu Loc-Thi Nghe Canal in Ho Chi Minh City on August 2, 2016. Photo: Tuoi Tre

Dead fish and litter in the Nhieu Loc-Thi Nghe Canal are seen being collected in a net on August 2, 2016. Photo: Tuoi Tre

Litter and smudge thickened a part of the Nhieu Loc-Thi Nghe Canal in Ho Chi Minh City on August 2, 2016. Photo: Tuoi Tre

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