Abstract: PROMOTING GROWTH OF FRY AND ADUIT FISH BY IRRADIATING FISH EMBRYOS WITH LOW-DOSE OF Ra_Be NEUTRON SOURCEYu Yongcheng（Fishfarm of Nanzheng county of Shangxi province, 723100）Zhang Yuhua；Wu Jilan（Departement of Technical Physics,Peking University,100871）AESTRACI Proper neutron dose can stimulate fries to grow. The optimum neutron fluence is from9．2×10~5cm~(-2)to 18×10~5 cm~(-2)．The yield of fries is increased by 16％─24％（silver carp fries） and 6％─30％（carp fries）． The cultivated period of the treated silver carp fries is shortened by 28─45 days（1／3 to 1／2 period）．The irradiated embryos of silver carp and carp are reared and produced for com-mercial adult fish in 1992. Key words Ra-Be neutron source fish embryo fry irradiation