Malachite green residue in farmed fish in north-west part of Iran.

The occurrence of malachite green (MG) residue was determined in 177 farmed fish samples (i.e., 85 carp, Cyprinus carpio, and 92 rainbow trout, Oncorhynchus mykiss) purchased from north-west part of Iran from 2014 to 2015. Competitive enzyme immunoassay method validated according to the criteria of Commission Decision 2002/657/EC was used to determine the MG residue. The mean recoveries were in the range of 79.1-86.2% and the limit of detection of the method was 0.30 μg/kg. The value of detection capability for MG in fish muscle was less than 1 μg/kg, which was below the minimum required performance limit of 2 μg/kg. MG was detected in 108 fish samples, corresponding to 61.0% of the total examined samples, ranging between 0.35 and 7.12 μg/kg. Most of the contaminated samples (28.8%) contained MG at the level of 0.3-1 μg/kg. Altogether, 18 out of 177 samples contained residue of MG higher than 2 μg/kg. The results indicated that the usage of MG in Iranian fish farms is frequent. It is alarming and could be a potential hazard for public health. [ABSTRACT FROM AUTHOR]