Short-term imidacloprid exposure in juvenile fish triggers physiological and biochemical responses

The extensive use of systemic neonicotinoid insecticides in agriculture is a significant factor contributing to pollution in aquatic systems. Currently, there is no comprehensive data available on the effects of imidacloprid and other neonicotinoids on fish ( Clarias gariepinus ) biochemical and behavioral parameters. Several biomarkers, as well as mortality, behavioral alterations, and biochemical changes, were assessed to determine the impact of imidacloprid on Clarias gariepinus . The results demonstrated a substantial difference in fish mortality after exposure to imidacloprid (96-h LC ₅₀ = 166.60 mg/L) and the fish behavior varied with concentration and time of exposure. A significant difference (p = 0.0140) in mortality was observed in fish exposed to imidacloprid compared to the control. All exposed fish showed noticeable distress symptoms, represented by under-reactivity to stimulus, hypoventilation, gulping, abnormal surface distribution, and poor swimming movement. The GPx activity of control and exposed fish differed noticeably ( p <0.05) at 130 mg/L. The alteration of several hepatic biomarkers of fish exposed to imidacloprid observed in this study indicates potential damage to the liver, which is a vital organ responsible for the detoxification and metabolism of xenobiotics. The results from this study could be used as a baseline for future research investigating the long-term effects of imidacloprid exposure on fish and other aquatic organisms