湖南省隆回县金石桥镇两位承包小型水库养鱼的农民反映:2000年他们投资上万元的资金又打了“水漂”,所放的数万尾鱼种“回捕率很低,没有发挥应有的经济效益。这一现象普遍存在。原因何在?主要有以下几种。(一)放养鱼种规格小。水库面积有大有小。但总的来说,比鱼塘面宽、浪大,鱼类多。若放养的鱼种规格小、体质弱,对环境的适应力较差,成活率就低。加之,“大鱼吃小鱼”,因此,水库所放养的鲢、鳙鱼种一般应在13cm 以上,草、青龟种应在16cm 以上。一些新建造水库敌害少,可适当降低放养规格,但不能小于10cm。(二)品种搭配不合理。导致鱼类生长慢、产量低。水质清瘦的水库,应以投放鳙鱼为主,配放少量白鲢。水质较肥的水库,应以放养白鲢 Two peasants contracting small-scale fish farms in Jinshiqiao Town, Longhui County, Hunan Province, reported that in 2000, they invested tens of thousands of yuan in funds and made “water drift”. The tens of thousands of tail fish species they put have a low recovery rate , Did not play its due economic benefits.This phenomenon is widespread.What are the main reasons? There are mainly the following: (1) Species of stocking small size reservoirs are large and small, but in general, than the surface of the fish pond Wide, big waves, fish and more .If the stocking of small species size, physical fitness is weak, less adaptable to the environment, the survival rate is low.In addition, the “big fish eat fish”, so the stocking of silver carp , Catfish species should generally be more than 13cm, grass, green turtle species should be more than 16cm. Some newly built reservoirs fewer enemies, may be appropriate to reduce stocking specifications, but not less than 10cm. (B) with a variety of unreasonable. Cause fish Slow growth, low yield. Thin water quality reservoirs should be put into the main anchovy, with a small amount of silver carp. Water quality of fat reservoirs should be stocking silver carp