About 1,000 kg of turbot were put onto the market in Beijing on Tuesday, the first time after the lifting of a month-long sales ban imposed after carcinogens were detected in the fish in Shanghai.

The batch of turbot produced by fishery companies in Huludao, northeast China's Liaoning Province, has been approved by the Beijing Food Safety Office, said Wang Jianhua, who works in the office.

Due to their low resistance to disease, the fish introduced to China from Europe in 1992 are sometimes fed large quantities of medicinal supplements, which can leave harmful residues in their flesh.

The recent scare regarding turbot sales in Beijing and other cities reflects loopholes in food safety monitoring, according to Lei Jilin, the man who introduced the flatfish to China.

"There is no quality control before the fish enter the market, even though government departments are supposed to do that," said Lei, member of the Chinese Academy of Sciences and a researcher with the Yellow Sea Fishery Research Institute of Chinese Academy of Fishery Sciences.

China produces 55,000 tons of turbot every year, of which 70 percent is produced in the eastern province of Shandong.

The turbot industry suffered great damage after carcinogens were detected in Shanghai and the sales bans were enforced. It is estimated there were 50 million fish totaling 25,000 tons in Shandong that could not be sold.

(Xinhua News Agency December 28, 2006)