On the morning of 4/5, Tran Van Huy, 38, rowed his boat to check his cage farms on the Lam River in Anh Son commune. He found a dense layer of fish floating belly-up, while others swam sluggishly before dying. "I have been farming fish for more than 10 years, and this is the first time I have witnessed such a sight", he said.

Tran Van Tuong's fish farm experienced a similar situation. Hundreds of large carp floated lifelessly on the water's surface, scattered throughout the cages.

Tuong stated that his family had cared for this batch of about 350 fish for three years, and most were ready for harvest. This morning, when feeding them, he noticed smaller fish swimming weakly. Within hours, larger fish also began to die, and the situation became irreversible.

Tuong distraughtly collects dead fish for disposal. Photo: Hung Le

In nearby cage farms, residents continuously collected dead fish, loading them onto boats or bringing them ashore for disposal. The deceased fish were mainly carp, rohu, silver carp, and catfish, weighing from 0,5 to 3 kg each. Along the river, some wild fish species also died, drifting to the banks.

Vo Van Phung, 64, reported that his family primarily raises grass carp, with each cage containing 200 to 500 fish, nearing harvest time. "We estimate losses of over one ton of fish. Since the cause is unclear, we are just collecting them for burial to prevent pollution", he explained.

According to residents, cage fish farming on the Lam River has historically been stable due to good water circulation and high oxygen levels, allowing fish to grow quickly and be easily sold. This incident puts many households at risk of losing tens of millions of dong entirely after a long period of investment.

Bui Thanh Dung, Vice Chairman of Anh Son Commune People's Committee, stated that specialized agencies are currently assessing the damage and collecting samples to determine the cause. This marks the first time the locality has recorded widespread fish deaths.

"Specialized agencies are inspecting the site and analyzing water samples; initially, the possibility of abnormal water environmental fluctuations has not been ruled out", Dung said.

Some residents reported that on the afternoon of 3/5, the area experienced thunderstorms and hailstorms following several days of intense heat. This sudden change may have caused abrupt environmental shifts in the water, affecting the fish population.

Across Anh Son commune, approximately 20 households operate cage fish farms on the Lam River, most of which have been affected. This afternoon, many people are attempting to salvage any surviving fish to sell and offset losses.

Dead fish collected by residents fill a boat's hold. Photo: Hung Le

On the afternoon of 3/5, thunderstorms and hailstorms lasting 10-25 minutes occurred in several communes formerly part of Anh Son district. In Thanh Binh Tho commune, many hailstones the size of chicken eggs fell, damaging 193 houses and flattening 112 hectares of spring rice. A storage tank belonging to Song Lam Sugarcane Joint Stock Company in Nhan Hoa commune was struck by lightning, causing 2,000 liters of molasses to spill, resulting in billions of dong in damages.

In Ha Tinh, thunderstorms and hailstorms on the afternoon of 3/5 damaged nearly 5,900 hectares of spring rice. Cam Trung commune alone saw over 600 hectares of unharvested rice affected, 18 houses had their roofs blown off, and two electricity poles collapsed. Many localities, including Bac Hong Linh, Ky Xuan, Duc Thinh, and Duc Quang, suffered hundreds of hectares in damages.

Duc Hung