Aim:
The study aims to analyse the acute and chronic effects of the Spinosad insecticide on common carp (Cyprinus carpio Linnaeus, 1758). Aquatic ecosystems face increasing threats from agricultural runoff, especially pesticides.

Material and methods:
Acute toxicity tests were conducted over 96 hours with six concentrations of spinosad (2.5, 5.0, 6.25, 7.5, 8.75, and 10.0 mg/L) to determine the median lethal concentration (LC50) and observe behavior. For chronic exposure, carp were exposed to three sublethal concentrations (1.25, 3.75, and 5.0 mg/L) for 20 days. Key physiological indicators, including blood cell counts, hemoglobin levels, liver enzyme activities (AST and ALT), and liver histology, were assessed for any histopathological changes.

Results:
Acute toxicity tests show an LC50 of 7.41 mg/L for spinosad in common carp, with behavioral changes more noticeable at higher concentrations. Chronic exposure caused significant alterations in hematological parameters (RBC, WBC, PCV, and Hb), increased liver enzymes (AST and ALT) with longer exposure times (P ≤ 0.001 for AST; P ≤ 0.0001 for ALT). Histological analysis revealed liver damage, including vacuolation, swelling, and necrosis, with severity rising with concentration and exposure duration.

Conclusions:
This study shows that spinosad, labeled as a "reduced-risk" pesticide, causes significant short-term and long-term toxicity in common carp, affecting behavior, blood parameters, liver enzyme activity, and tissue health. These results emphasize the environmental dangers of spinosad runoff from agricultural fields and underline the importance of careful use and monitoring to protect aquatic ecosystems. More research is needed to explore the long-term impacts on non-target aquatic species.