“1985年7月27日雷雨前,云梦县养鱼大户甘云山的16亩精养鱼塘,突然死鱼830斤。”“1985年8月11日早晨,汉川县刘隔乡养鱼大户王武波的6.4亩鱼种池,鱼大量死亡,损失4700元。”不幸的告急声接踵而来,令人震惊。据调查分析,鱼塘缺氧是鱼大量死亡的主要原因。鱼塘含氧量的大小不仅与外界温度、气压有关,而且取决于鱼的放养密度。鱼的放养密度愈大,鱼塘缺氧愈为严重,而增加放养密度是提高单产的重要措施。因此要提高鱼的单产,必 “July 27, 1985 before the thunderstorm, Yunmeng County, a large fish farming Ganlun 16 acres of intensive fish ponds, suddenly dead fish 830 pounds. ” “August 11, 1985 morning, Large fish farmer Wang Wubo’s 6.4 acres of fish ponds, a large number of fish died, the loss of 4,700 yuan. ”Unfortunately, the unfortunate emergency followed, shocking. According to the survey and analysis, fish pond hypoxia is the main reason for the large number of fish deaths. Fish pond oxygen content not only with the outside temperature and pressure, but also depends on the stocking density of fish. The greater stocking density of fish, fish ponds more serious hypoxia, and increase the stocking density is an important measure to improve yields. Therefore, to raise fish yields, it is necessary