Residents in Ky Anh Town in central Ha Tinh Province have found dead fish floating in the local Quyen River since last week.
Dead fish are taken to the river bank by locals to be buried.
They believe the deaths are linked to Formosa, the company whose toxic spill killed a large quantity of fish in the ocean last year.
Hoang Van Uan, a resident, said he discovered the dead fish scattered in different sections of the river. Uan said residents buried the dead fish in a nearby field.
Phan Duy Vinh, the town’s deputy chairman, affirmed the recent mass fish deaths. However, according to him, the deaths were caused by muddy water that farmers released from their paddy fields in preparation for a new crop.
Vinh said there were no fish deaths in the lower part of the river.
Managers in Ha Tinh Economic Zone, which include the Hung Nghiep Formosa Steel Corporation, said the company has a canal for irrigation in the river basin, but it does not meet the water. A manager added that Formosa is located near the lower part of the river, away from where the deaths occurred.
Meanwhile, although fish deaths continue to be reported, concerned agencies have not yet taken water samples for testing.