This study aimed to investigate the concentrations of Cd, Cr and Pb in the water and sediment, and to compare the concentrations of these metals in fish muscles, the levels of plasma oxidative stress biomarkers (malondialdehyde and protein carbonyl) and the genetic differentiation between experimental tilapia fish from the contaminated reservoir near municipal landfill and the reference area after chronic exposure to the metals. The concentrations of Cd, Cr and Pb in the water exceeded the Thailand water quality standard, whereas the concentration of Cd in the sediment exceeded the Thailand soil quality standard. The concentrations of these metals in fish muscles were below Thailand food quality standard. In comparison to the reference fish, the fish in the landfill reservoir revealed a significant increase in malondialdehyde and protein carbonyl (p < 0.05). The dendrogram results demonstrated values of genetic similarity for the fish from the reference and the landfill areas at 0.84-0.94 and 0.65-0.97, respectively, implying that the values of genetic differentiation as a consequence of genotoxicity of the fish from the landfill were greater than those of the fish from the reference area. The results indicate that chronic heavy metal exposure could induce oxidative stress and genotoxicity of tilapia fish in the reservoir near municipal landfill.

This study aimed to investigate the concentrations of Cr, Cd and Pb in the water, sediment and experimental hybrid catfish muscles, and to compare the genetic differentiation and the levels of oxidative stress biomarkers (malondialdehyde and protein carbonyl) between the catfish from the contaminated reservoir near a municipal landfill and the reference area after chronic exposure. The concentrations of all metals in the water and the concentration of Cd in the sediment exceeded Thailand’s surface water quality and soil quality standards, respectively, whereas the concentrations of these metals in fish muscles did not exceed Thailand’s food quality standards. Dendrogram results in terms of genetic similarity values of the catfish from the reference and the landfill areas were 0.90 to 0.96 and 0.79 to 0.86, respectively, implying that the genetic differentiation of the fish from the landfill was greater than of those from the reference area. The fish in the landfill reservoir had slightly increased protein carbonyl levels. The results indicate that chronic heavy metal exposure can cause genotoxicity of the hybrid catfish and induce protein carbonyl as an oxidative stress biomarker in the reservoir near a municipal landfill.