The increasing use of synthetic insecticides in agriculture poses a significant threat to aquatic ecosystems, especially fish species, through runoff and leaching into freshwater bodies. However, the degree of insecticide toxicity is not uniform and varies with the physicochemical parameters of water such as pH, temperature, dissolved oxygen, hardness, and salinity. This paper aims to investigate how these water quality parameters influence the bioavailability and toxicity of insecticides in fish. It explores the interactive roles of water chemistry and pesticide behavior in altering fish physiology, behavior, and mortality. Understanding these interactions is crucial for ecological risk assessment and sustainable aquatic management.