Advances in Life Sciences

The tissue of heart was taken to observe the effect of thermal stress for prolonged periods. In testis the cold stress caused shrinkage is inter cellular space and size of seminiferous tubules and in ovary at heat stress at 18 hrs. and 24 hrs. caused swelling of ovarian follicle and appearance of large black dot like structure cold stress caused shrinkage in size of ovarian follicle. However, the thermal stress applied for prolonged period in the form of heat or cold stress is always unfavorable to the breeding rate of H. fossilis. Temperature related stresses are very important environment stress, as during summer and winter there are excessive rise and false in the environmental temperature more over, thermal stress applied by earlier worker are in the form of acute stress by sudden transfer of the fish to varying temperature. Thus they amount to be more as shock than stress. The Magnitude of initial effect varies with the amount of temperature changes.