Acute Toxicity of Paraquat to Various Developmental Stages of Common Carp, Cyprinus carpio Linnaeus

The toxicity of the herbicide paraquat (methyl viologen) was evaluated in various developmental stages of common carp, Cyprinus carpio L., namely yolk, post-yolk, fry, and fingerling. Bioassay was performed for a period of 96 h, and median lethal concentrations (LC50) were determined for all stages. The LC50 values at 96 h for yolk, post-yolk, fry, and fingerling stages were 11.3, 33.3, 67.5, and 134.1 ppm, respectively. These results show that the tolerance of carp to paraquat increases with the development of fish. Severe damage was observed in various organs of the fish exposed to 178 ppm paraquat for 96 h. Among histopathological changes, nucleic pyknosis in epithelial cells of renal tubules and in parenchymal cells of the liver was most prominent.