On 6/5, the Nghe An Province Fisheries and Fisheries Resources Sub-Department stated that observations of fish refusing to eat, surfacing, dying quickly, and showing no signs of hemorrhage in their color or internal organs, coupled with the widespread and simultaneous nature of the phenomenon affecting wild fish as well, indicate that the cause is likely due to poor environmental quality. This includes a sudden lack of dissolved oxygen in the water or the impact of toxic gases.

Specialized officers assessed this incident as an environmental fluctuation, leading to an abrupt and widespread decline in water quality, rather than a common disease.

According to an inspection of the fish farming area on the Lam River, specifically in the section passing through Kim Nhan 1 hamlet, Anh Son commune (formerly part of Anh Son district), heavy rain accompanied by thunderstorms and lightning occurred on the evening of 3/5. From 5-7 AM the next morning, the Lam River's water turned muddy yellow. No strange odors or oil slicks were detected, and some water quality indicators remained within suitable ranges for freshwater fish.

People in Anh Son commune collecting dead fish for disposal, 4/5. Photo: Duy Thanh

The Fisheries and Fisheries Resources Sub-Department described this as an unusual and rapid event, occurring on a section of the river known for strong currents. As there are currently no farmed fish remaining in the cages, determining the specific cause has become challenging.

On 4/5, approximately 8,6 tons of farmed fish, including grass carp, black carp, sheatfish, and catfish, died across 19 cages on the Lam River in Anh Son commune. This incident resulted in hundreds of millions of dong in losses for 13 households. No further fish deaths have been reported since then.

A day before the fish kill, several communes previously within Anh Son district experienced thunderstorms with hail that lasted between 10-25 minutes. In Thanh Binh Tho commune, hailstones the size of chicken eggs caused damage to 193 houses and flattened 112 hectares of spring rice. Additionally, a storage tank at the Song Lam Sugarcane Joint Stock Company in Nhan Hoa commune was struck by lightning, leading to a spill of 2,000 liters of molasses and billions of dong in damages.

Duc Hung