ON THE GROWTH RATE OF SILVER CARPS FROM DIFFERENT SOURCES OF CHANGJIANG RIVER AND ZHUJIANG RIVER

An attempt has been made to compare the growth rate of silver carps from dif-ferent sources.They are, a group of wild silver carp and a group of domesticated silver carp from Changjiang River, and a group of wild silver carp and，group of domesticated silver carp from Zhujiang River. Experiments were parried out in fish rearing ponds, net cages and self-purification round ponds. In each experiment the fish of 4 groups reared were mingled and each group was marked by fin-clipping.The fish were reared from 2 months to lfi months old, the total length were from 12 cm to 39 cm, and the body weight were from 16g to 605g.Results showed that a regular differerence of growth rate existed within the 4 groups of silver carp. fn spite of wild or domesticated, the two groups from Zhujiang·River grew fast in the first year，then slowed down in second year. On the contrary,silver carp from Changjiang River appeared slow in the first year and rapidly pragres-sed in the second year. Consequently。surpassing weight of 28---66 g offer Zhujiang River silver carp was produced. The order of growth rate of the 4, groups were:Changjiang wild silver carp>Zhujiang wild silver carp>Changjiang domestic silver carp>Zhujiang domestic silver carp.