Paraquat Dichloride is a herbicide and continues to be the third most widely used herbicide in the world and indisputably one of the most extensively employed weed killers in India. The content of this book reveals the toxicological response induced by Paraquat dichloride on the fresh water mud eel (Monopterus cuchia), exploring the effects on physiological, biochemical changes and the expression of molecular chaperones as a marker of oxidative stress.