The present study deals infection of particular parasite and particular impact on host fish species. Different histochemical reactions showed localization of different chemicals. With the Moreover, the histochemical investigations provide an insight into the nature of various physiological and pathological processes in the gastrointestinal tract occurred due to parasites. It has been observed that the different constituents are stimulated by particular parasite and particular loss in different organs of the digestive system of the fish studied. Histochemical study may provide a valuable with low cost-effective tool for the diagnosis of diseases in histopathology, parasitic investigation and for the researchers in histopathology. The present study includes the histochemical analysis of Procamallanus species infected fish intestines in Mastacembellus armatus.