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罗非鱼的养殖现已推广,但因其成熟早,养殖过程中过早繁殖,而造成养成规格小、产量低的现象。山东省淡水水产研究所利用尼罗罗非鱼和奥利亚罗非鱼进行杂交,制得90％以上的全雄罗非鱼。全雄罗非鱼具有生长快,养成规格大、抗病力强、易饲养等优点,值得推广。现将其制种技术介绍如下: 一、亲鱼的选择: 1.雌雄罗非鱼的鉴别:区别雌雄主要是观察体色和生殖孔。在生殖季节,雄鱼体色鲜艳,头部及两侧微红,纵纹带消失,胸鳍、尾鳍、背鳍边缘呈淡红色;雌鱼呈灰黑或暗灰色。雄鱼有二个近邻的开孔,即肛门和泌尿生殖孔。泌尿生殖孔系肛门后一个小圆柱凸起,其顶端仅为一圆点,在生殖季节,其圆柱凸起常突出略下垂,挤
Tilapia breeding has now been promoted, but due to its early maturity, breeding premature breeding, which led to the development of small size, low yield. Shandong Institute of Fresh Water Fisheries made use of Nile tilapia and Oreochromis hybrids, resulting in more than 90% of the entire male tilapia. Whole-breed tilapia with fast growth, develop a large specification, disease resistance, easy to raise, etc., it is worth promoting. Seed production technology now introduced as follows: First, the choice of broodstock: 1. Male and female tilapia identification: the difference between male and female is mainly observed body color and reproductive pores. In the reproductive season, male body color bright, reddish head and sides, vertical veins disappear, pectoral, caudal, dorsal fin pale red; gray or dark gray females. Male fish have two neighbors of the hole, that is, anal and genitourinary holes. Urogenital orifice Department anal an a small cylindrical bulge, the top is only a dot, in the reproductive season, the bulge often protruding slightly drooping crowded