Two samples of freshwater grouper have been found with trace amounts of malachite green in the latest round of tests for the chemical, the Centre for Food Safety says.

The samples were taken from two stalls at Tai Po Hui Market. The stalls have been ordered to stop selling the fish in question.

The centre will trace the source of the chemical. If there is sufficient evidence, prosecution action will be taken.

As the level of malachite green detected in the samples is low, normal consumption should not pose any adverse health effects, the centre said.