Determination of malachite green and leucomalachite green residues in rainbow trout in Sanandaj City

Malachite green (MG) is an organic compound which his used as a dye in textile industry. This compound is applied incorrectly and illegally in aquiculture as an antimicrobial agent. This compound has mutagenic and carcinogenic effects.

In this study we determined the concentrations of MG and leucomalachite green (LMG) in the muscle tissue of 90 rainbow trouts (Oncorhynchus mykiss) collected from the local markets in Sanandaj City within a period of six months in 2018. In order to measure the residues of MG and LMG, we used enzyme-linked immunosorbent assay (ELISA) based on the European Union Decision 2002/657/EC.

The results showed presence of MG and LMG in all 90 samples: The residues of MG in the samples were as follows: 1-2 μg/Kg in 41 (6.45%), more than 2 μg/Kg in 45 (50%) and less than 1 μg/Kg in 4 samples (4.4%). Furthermore, the residues of LMG in the samples were as follows: more than 2 μg/Kg in 13 (45.14%), 1-2 μg/Kg in 67 (44.74%) and less than 1 μg/Kg in 10 samples (11.11%).  Moreover, the limit of detection (LOD) in the method was 0.43 μg/Kg.

 It is concluded that MG is illegally applied in fish farms, which can be a threat to human health and the environment.