This book provides glimpses into the recent ‘Mechanisms of toxicity in fishes’ and it is first such holistic and explicable attempt, incorporating a comprehensive update account of the heavy metals as water pollutants and almost every essential fundamental aspect about their chronic toxicity in fishes. The book has 2 parts and each is well defined to its contents in total 14 chapters, such as ‘Scope of water pollution and the important definitions; Industrial and non-industrial water pollutants; Metal epidemiology; Occurrence of heavy metals in water bodies; Metal uptake and their accumulation in fish tissues; Health risks of metals in fishes; Symptomatic morphological and behavioral aberrations; Metal induced biochemical changes in fish tissues; Hematological and Immunological alterations; Enzymatic alterations; Stress proteins and a specific chapter on ‘The Oxidative stress and the Arsenic toxicity’. This book will essentially be of much importance to the fish scientists, ecologists, and the agricultural scientists working in various state universities and ICAR institutes.