Turbot has been banned from all markets following confirmation that cancer-causing chemicals had been found in two of five samples, the Centre for Food Safety said yesterday.
The centre's acting controller, Ho Yuk-yin, said malachite green was discovered in the flatfish taken from stalls in a Sham Shui Po wet market and the centre was tracing the origins.
The centre said the concentrations of malachite green in the two samples were 340 and 480 micrograms per kilogram respectively. A kilogram contains a billion micrograms. It said the levels were low.
'We have been liaising closely with the [fish] importers and we have secured their co-operation not to import turbot fish from the mainland for the time being,' Dr Ho said. 'If we still find any turbot fish in the market, we will mark them and seal them and stop their sale.'
The centre would consider prosecuting the stalls when testing on the samples had been completed.
Chamber of Seafood Merchants chairman Lee Choi-wah said almost all turbot available came from farms on the mainland.