Residues of Malachite Green in Fish Originating From German Rivers

Malachite green is a widely used triphenylmethane dye for coloring synthetic fibers, silk, leather and paper. Although it is additionally an effective veterinary drug for the treatment of various fish diseases, it may not be applied to fish intended for human consumption. Due to indications from laboratory studies the European Food Safety Authority (EFSA) classifies malachite green as a potentially genotoxic and/or carcinogenic compound. For this reason the zero tolerance principle is applied for this compound and its metabolite leucomalachite green in Europe. A minimum required performance level (MRPL) of 2 µg/kg was established for the sum of malachite green and leucomalachite green.  Fish samples containing traces of either malachite green or leucomalachite green are not marketable.

Since in 2007 malachite green was identified as an environmental contaminant (Heberer et al.) untreated, free-living breams originating from 17 different locations in Germany  were analyzed by using LC-MS/MS. Concentrations up to 0.9 µg/kg leucomalachite green were detected in an animal, which was caught in the Rhine at Koblenz. Residues of malachite green were preferably detected in fish samples coming from water bodies located in areas with strong industrial influence and high wastewater content. Similar observations were previously described by Heberer et al. in case of eels originating from municipal water bodies in Berlin. The analytical method and detailed results will be presented.