Objective To monitor and assess the residues of malachite green(MG)and its metabolites leucomalachite green(LMG) in freshwater fish.Methods Twenty eight kinds of 207 fish samples were collected from retailers in six cities of Fujian Province.After samples being homogenized and pre-treated,the concentration of total MG in samples was quantified by high performance liquid chromatography(HPLC) coupled with fluorescence detector.The positive samples analyzed by HPLC were confirmed by HPLC-mass spect...