一、前言枝角类是淡水鱼类营养价值很高的优良天然饵料,研究枝角类的生态是了解水体生产力,合理利用鱼类饵料资源的主要内容之一。大型溞(Daphnia magna Straus)是广温性的世界种,在我国分布也很广。文献中已记载的地区有江苏、安徽、山东、河南、河北、辽宁、吉林、黑龙江、内蒙古、山西、陕西、甘肃、青海、西藏。大型溞即 I. Preface Cladocera is an excellent natural food with high nutritive value of freshwater fish. Studying the ecology of Cladocera is one of the main contents of understanding the productivity of water bodies and making rational use of the fish food resources. Daphnia magna Straus is a broad-bodied world species and is widely distributed in our country. The documented areas include Jiangsu, Anhui, Shandong, Henan, Hebei, Liaoning, Jilin, Heilongjiang, Inner Mongolia, Shanxi, Shaanxi, Gansu, Qinghai and Tibet. Large 溞 that is