各国淡水栽培渔业对象的种类组成和饲养数量,大多取决于下列条件:具备不管哪一种类型的水域;国家的基本技术和工艺水平;市场上固有的需求和供应;购买力;对栽培对象的消费习惯。例如,美国的主要饲养对象是沟鲶,因为鲤鱼被认为是低值鱼。挪威主要是在沿温流环绕的岸边安装的网箱里大量地饲养鲑科鱼类。非洲栽培罗非鱼、鮡科鱼类;东南亚栽培虱目鱼、鲤鱼、草食性鱼类和虾类。应当指出,近年来,许多国家开始兴致勃 The composition of the species and the number of rearing fisheries targeted for freshwater aquaculture in each country depend largely on the following conditions: availability of irrespective of the type of water; basic technical and technological level of the country; inherent demand and supply in the market; purchasing power; consumption of cultivated objects habit. For example, the main breeding animal in the United States is ditch catfish, because carp is considered a low-value fish. Norway stocks large numbers of salmonids in cages installed along the shoreline of warm streams. African cultivation of tilapia, gynostemma; Southeast Asia cultivation of milkfish, carp, herbivorous fish and shrimp. It should be pointed out that in recent years many countries have begun to flourish