Photo taken on Nov. 1, 2005 shows a market selling freshwater fish in Hong Kong. (File Photo)   Nov. 27 - Another type of freshwater fish imported from the mainland and sold in Hong Kong has been found to be contaminated with cancer-causing chemical malachite green.

 

The detection of the banned substance in mud carp brings to four the number of freshwater-fish types found to have been tainted - after the flat turbot fish, garoupa and bream.

 

Ho Yuk-yin, acting controller of the Food Safety Centre, revealed Sunday that one of 18 mud carp samples tested was found to contain the toxic chemical. The samples were collected from the Cheung Sha Wan Wholesale Food Market and imported from a registered fish farm in Foshan, Guangdong province.

 

Ho said the center has informed Beijing, and Guangdong authorities have stopped the export of freshwater fish to Hong Kong from the farm.

 

The latest revelation followed confirmation Saturday that a bream, also from a registered fish farm in Guangdong, and 11 of 15 samples of the freshwater garoupa contained small traces of malachite green.

 

Malachite green is a synthetic dye used to color silk, wool, jute, leather, cotton and paper, and used to treat fungal infections at fish farms. Scientists say high levels of the toxin may cause cancer and changes in DNA.

 

All freshwater fish supplied by registered farms to Hong Kong should be certified chemical-free.

 

But Ho said the testing is "not 100 percent perfect."

 

"The key is that we have a monitoring mechanism and can promptly trace the source," he said.

 

Local vendors Sunday stopped importing 40 types of freshwater fish, shrimp and crab from the mainland.

 

Permanent Secretary for Health Welfare and Food Carrie Yau Tsang Ka-lai will leave for Beijing today for talks with officials from the State General Administration of Quality Supervision, Inspection and Quarantine on food safety issues. She will be accompanied by Mak Sin-ping, controller of the Centre for Food Safety.