Eight groups of eyed eggs were subjected to gamma-ray doses of 100, 200, 400, 500, 600, 800, 1000 and 2000 rads, respectively. All the groups were incubated after irradiation and the fry were reared until they reached a mature stage.
There appeared no differences in the rate of hatching among the eight groups. However, all the fry which had received above 800 rads of the gamma-irradiation died before reaching the advanced fry stage, whereas 50 to 80% of the fry which were subjected to less than 600 rads survived. A high percentage of deformed alevins was observed in the 2000 rads group.
In the groups exposed to more than 400 rads of gamma-rays the percentage of fully muture fish decreased with the increase in gamma-ray dose. This phenomenon was observed more markedly in the females than in the males.
In the groups which received less than 200 rads the percentage of mature fish was similar to that of the unexposed control group.