Water Quality and Fish Health: Interaction with Toxic Substances

Water quality is an important factor for the well-being of aquatic ecosystems, it also influences physiological, behavioral and biochemical activities of water animals including fish. Due to overpopulation, lack of awareness and lack of implementation of environmental laws, there is an increase in the variety of toxic compounds in water bodies whose adverse effects have been widely distributed among aquatic biotas. Fish, being fragile animals, is affected by changes in the physical and chemical constituents of the water. This chapter highlights the hazardous effects imposed by the influx of heavy metals, acid rain, pesticides, herbicides, petrochemicals, radioactive substances, plastics, microplastics and other industrial and domestic effluents and their byproducts on the wellbeing of fish. Toxic substances in aquatic environments result in a wide range of impacts on fish health and its survival. Various hazardous compounds and their metabolites cause stress responses, disrupt endocrine systems and impair growth and reproduction in fish populations. One of the major goals of the United Nations for the coming years is to ensure the safety and suitability of life under water indicating its importance for human health and sustainable development for a prosperous future. There is a need for hours to monitor water quality parameters furthermore, more rigorous monitoring and control of water quality standards to protect aquatic life from the escalating threat of environmental pollution.