It has long been assumed that the farm fishes [Mylopharyngodon piccus(Richardson),Ctenopharyngodon idellus(Cuv. et Val.),Hypophthalmichthys molitrio (Cuv. et Val.)，Arislichthys nobilis (Richardson)]cannot propagate whear they live in thn environment of the pond. After the study of the development of the gonads of these fishes, this view proves to be wrong. In 1058, Nanhai Fishereis Institue, Ministry of Fisheries succeeded in some experiments on the artificial propagation of the pondxeaxed H.molitris and A. nobilis, and the investigators of Iluzzan and Canton succeeded in the artificial propagation of U. idellus in 1960. With the popularization of technical shill and the development of production,research on fundamental theories has been carried an widely and fruitful results have been acheived in the development and maturation of the oocyte, cytology of fertilization, development of embryo, the mechanism of ovulation and cyto-chemistry. The ovcytea of these pond-reared fishes can only develop to the fourth stage (priwary oocyte),Estrualixation is indispensable for the oocytes to develop from tire fourth to the fifth stage (secondary ooeyte).Oocytes and follicular cclls are of the Same origin, bath derived from the germinal epithelium of the wall of the ovary, The ovaries of farm Fiches st the age of sexual maturation pass the winter in the third stage or from the second to the third. They develop to the fourth stage from April to May, and reach full maturity from May to June. The appearance of physiological death (degeneration) of some oocytes begins in late June, then degeneration exEends to all in August and November. The farm fishes are of the type of spawning vuly once a year. hstrualization prodnccs two rffects upon ovcytes, i. e. maturation and ovulation. The rnaturation and ovulation of oocytes arc two parallel and independent processes and the completion of these two processes requires the action of exogenous hormones in farm fishes. The cytological changes of vvcytea front the fourth stage to the fifth are as fal-ows; (1) nucleus goes under division acrd the first polar body is Given off; (2) follicular cells dissolved and eggs being set free; (3)microgylar cells disappeared;(4) cytoplasm which scatters between the spaces of the yolk floss tvwared the mi-cropyle, Only one sperm penetrates the ovum through the mieropyle, and it is known as monspermic egg. The first diviai.on takes place about 40---45 minutes after fortilixation at the temperature of 24-26℃. The main factors which influence the development of the embryo are the quality.