Histopathological studies in organs like gill and liver of Catla catla (Hamilton) were made to assess tissue damage due to sublethal concentration of 1, 2 dichlorobenzene and provides a real picture of the detrimental effects and the involvement of the volatile organic compound toxicants in the major vital functions such as respiration metabolism and reproduction in aquatic animals. The gill of 1, 2 dichlorobenzene exposed fish exhibited edema, secondary lamellar with severe cytoplasmic vaculoation and mononuclear cell infiltration surrounding the stem of the primary lamellae, lamellar degeneration and haemorrhage. The liver of Catla catla exposed to 1, 2 dichlorobenzene showed multifocal necrosis of hepatocytes, psychosis, disintegration of cells and vacuolization. In addition internal haemorrhage was also seen. Such pathological changes were observed in all the tissues were more pronounced in sublethal concentration for 28 days of exposure at Onesecond, one-fourth, one-sixth and one- eighth of the LC50, i.e., (0.7, 0.35, 0.23and 0.175 mg/L) of the 96hrs LC50 value. The observation of the present study is to suggest that the damage of these tissues is caused by cumulative accumulation of 1, 2 dichlorobenzene in tissues. The results suggest that the 1, 2 DCB even in low concentration might be harmful to the aquatic organisms
