Tannery effluent was brought from the Puliyankannu Village, SIPCOT Industrial Estate of Ranipet, Tamil Nadu, India. The fresh water teleost, Tilapia mossambica was chosen as experimental animal. Chromium is the major constituent of tannery effluent, which is the heavy metal and highly toxic to aquatic fauna. The physico-chemical characteristic and oxygen consumption of tannery effluent were estimated. Histological changes in the liver and muscle of the experimental fish were observed. In the present investigation, the changes of histological structure of liver and muscle of Tilapia mossambica under chromium stress and toxic stress of tannery effluents on agriculture aquatic fauna were studied and the results are reported in this paper.