Comparative Hepatic Toxicity of Pesticides in Common Carp (Cyprinus carpio Linnaeus, 1758): An Integrated Histopathological, Histochemical, and Enzymatic Biomarker Approach

The intensive use of pesticides in agriculture poses serious risks to aquatic ecosystems and non-target organisms, yet toxicological data remain limited. This study evaluated the acute effects of three widely used pesticides-pirimiphos-methyl (10 and 60 μg/L), propamocarb hydrochloride (40 and 80 μg/L), and 2,4-D (50 and 100 μg/L)-on the liver of common carp (<i>Cyprinus carpio</i> Linnaeus, 1758), a sentinel species in aquaculture, but also a species equally important in risk assessment and environmental monitoring. Fish were exposed for 96 h under controlled conditions, and histopathological, histochemical, and biochemical biomarkers were analyzed. All tested pesticides induced significant histopathological alterations, predominantly circulatory and degenerative changes, with severity increasing at higher concentrations. Propamocarb hydrochloride and 2,4-D caused more pronounced and partly irreversible hepatotoxicity compared to pirimiphos-methyl. The histochemical assessment revealed altered glycogen metabolism, while the biochemical assays showed inhibition of key liver enzymes, including ALAT, ASAT, ChE, and LDH, indicating disrupted metabolic processes. These findings highlight the vulnerability of aquatic organisms to pesticide exposure and support the use of fish liver biomarkers as effective tools in ecotoxicology research. The study also emphasizes the need for stricter regulation and environmental monitoring of pesticide contamination in aquatic ecosystems.