In the present investigation static bioassay studies and histopathological changes in some tissues (gills, liver and kidney) induced by Lindane 20% E.C. in the fish Colisa fasciatus have been taken under consideration. 2. With the help of bioassay studies, the TLm were noted. The TLm values were 0.87, 0.78, 0.68 and 0.64 mg/l for the temperature range 17 degrees C to 20 degrees C and 0.60, 0.56, 0.46 and 0.41 mg/l for the temperature range 32 degrees C to 35 degrees C at 12, 24, 48 and 96 h respectively. 3. The statistical analysis of different factors such as concentrations, time and temperature range based on the observed data gave the following results: a) At both temperature ranges, survival rates at different concentrations and time are significant at 1% and 5% level. b) The difference in survival rates at different temperature range are insignificant both at 1% and 5pected survival numbers. The standard errors were also calculated for these two lines which gave the insignificant results and there was no much change in the shape of experimental and expected lines. 4. The histopathological changes in the tissues (gills, liver and kidney) shows the following results: a) In the case of the gills there was a loss of different types of cells i.e. respiratory cells and blood cells. Blood vessels were atrophied and the outer membrane of gill lamellae was ruptured. The erosion of the tips of the gill filaments were also observed. b) In the case of liver the outer membrane was ruptured. Some hepatic cells were vacuolated and some completely degenerated. The central areas were much affected. Due to the toxic effect, large splitting of tissues were found inside the liver. c) In the case of kidney the outer epithelium, the parenchymatous cells of renal tubules, cuboidal cells of uriniferous tubules were much affected. Due to the degeneration of the cells large spaces were formed inside the tissue. Much affection was observed in the central areas.
