QUẢNG NINH — Lack of oxygen has been blamed for causing the death of cobia (Rachycentron canadum) fish in six farms in the Bến Do area of north-eastern Quảng Ninh Province’s Cẩm Phả City between August 9 and 15.

The high density of fish was believed to have caused the lack of oxygen. Additionally, recent heavy rain in the area has changed the water environment, exacerbating the situation.

The explanation was released on Monday afternoon, after the provincial Animal Health Division and relevant agencies conducted inspections and took samples of the dead fish in six farms for tests.

According to local breeders, the number of dead fish had increased dramatically over the past few days, reaching amounts in tonnes.

Ngô Thị Chanh, a breeder from Cẩm Thủy Ward, said most of the 200 cobia fish in her farm, weighing 4 kilos each, had died since August 9.

Chanh said her family had many years of experience raising cobia fish and she had not made any changes to their diet.

"Thus, we did not know the reason why our fish suddenly died like that," she said.

However, the authorised agencies denied the number of dead fish amounted to tonnes.

Thiều Văn Thành, head of the provincial animal heath division, one of members of the inspection team, said the breeders claimed the number of dead fish was in the range of tonnes, but when the inspection team visited they found no evidence of this.

The total number of dead fish was estimated to be about 500 kilos, he said.

Phạm Văn Kính, vice chairman of the People’s Committee of Cẩm Phả City, said there were 163 fish farms across the city. All farms were checked and fish was found dead in several farms.

The situation was not comparable to the mass fish death, like several media recently reported, he said.

In response to the situation, the People’s Committee of Cẩm Phả City has ordered relevant agencies to instruct local breeders to farm fish following technical standards and immediately report to the committee if any abnormal phenomena were found. —VNS