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

Abstract 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 LC50 = 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