Evaluation of ovum storage techniques for reproductive studies of fishes

We compared dry masses of mature oocytes and ripe eggs from Etheostoma lync eum and Etheostoma caeruleum that were stored in varying concentrations of either formalin or isopropyl alcohol. In comparison to 10% formalin, alcoho l significantly reduced the weights of both mature oocytes and ripe eggs, w ith 25% isopropyl alcohol resulting in much smaller reductions than 50% iso propanol. Three percent formalin resulted in smaller decreases in the masse s of oocytes and eggs than the alcohol treatments, and not all comparisons with 10% formalin were significantly different. We recommend fixing specime ns and storing them and gametic cells removed from them in 10% formalin. In cases where specimens or eggs in alcohol must be used in addition to mater ial in formalin, correction factors (to formalin standard) should be develo ped, but the correction should not be made uncritically due to the varying effects alcohol may have among samples.