Tests of another four freshwater fish samples, all from local sources, have found no trace of malachite green, the Health, Welfare & Food Bureau says. Grey mullet and tilapia were the fish sampled.

The bureau has so far tested 66 samples of 14 types of freshwater fish - 30 local and 36 imported. Malachite green has been detected in 13 samples, all imported. A freshwater grouper was found to contain the highest level of the hazardous substance.

All imported samples of grey mullet, tilapia, milk fish, seabass, mud carp and yellow eel have tested negative for malachite green.