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一、时间 最好在春节前(即大量捕捞成鱼时)选留亲鱼。捕成鱼以水温6—12℃时为最好,这时鱼的摄食量减少,活动缓慢,鳞片紧,不易受伤。 二、年龄 选留亲鱼应达到或接近性成熟年龄。南方地区光照强,水的积温高,鱼类摄食时间长,数量多,生长发育快,四大家鱼一般要比北方早成熟1—2年。其性成熟年龄一般是:青鱼5—7龄,草鱼、花鲢4—6龄,白鲢3—5龄。雄鱼一般比雌鱼早成熟一年。
First, the best time in the Spring Festival before the election (that is, when a large number of adult fish fishing) to retain their broodstock. Catching fish to the water temperature of 6-12 ℃ when the best, then reduced food intake, slow activity, tight scales, not easy to be injured. Second, the age of the selected parent fish should reach or approach sexual maturity. Light intensity in the south, the water accumulated high temperature, fish feeding a long time, the number of large, rapid growth and development, the four major fish generally mature earlier than the north 1-2 years. The sexual maturity is generally: 5-7 years old herring, grass carp, 4-6 years old silver carp, silver carp 3-5 years old. Male males generally mature a year earlier than females.