淡水养殖鱼类优良性状退化的成因与对策近年来我区（六安地区）有些生产单位往往偏重于生产规模和生产能力的扩大，忽视对鱼类良种的选育，亲鱼长期得不到更新，近亲繁殖严重。养殖的鲢鱼和草鱼等品种表现为过早成熟，生长变慢，个体变小，抗病力下降。究其原因有以下几点... Causes and Countermeasures of Degradation of Fine Traits of Freshwater Fish Farmers In recent years, some production units in our district (Lu’an area) have tended to focus on the expansion of production scale and production capacity, neglect breeding of breeding fishes, broodstock have not been updated for a long time, Inbreeding is serious. Breeding silver carp and grass carp and other varieties showed premature maturity, slow growth, smaller individuals, decreased resistance to disease. The reason for the following points ...