苏联科技人员曾在卡霍夫水库和德聂伯水库,对鱼类在水体中的分布情况作了二年的研究观察。其所得结果简述如下。(1.)有11种鱼类作有规律性的昼夜垂直移动,即夜晚时升至水体的深水层或表层,白天下沉至近底层或库底。这样移动的情况明显地出现在7月、8月和9月中,在6月、10月和12月里也有出现。(2.)自黄昏开始,首先升至深水层的是 Soviet scientists and technicians once worked in the Khahov and Dnepr reservoirs for a two-year study of the distribution of fish in the water. The results obtained are summarized as follows. (1) There are 11 species of fish that move regularly both day and night, that is, they rise to deep water or surface waters at night and sink to near bottom or bottom during the day. This movement is evident in July, August and September, and also in June, October and December. (2.) From the dusk, the first rise to deepwater is