中文摘要：

于2003年9月、2006年4月和11月，分别对瑞丽江流域鱼类资源进行了3次实地调查，共采集到鱼类49种，其中包含1个鱼类属级新纪录及新种——小眼小波鱼（Microrasbora microphthalma）。结合历史资料及文献整理，瑞丽江共有鱼类60种，隶属8目、19科、44属；其中，伊洛瓦底江水系特有鱼类16种，外来引入种9种。鱼类组成上，以鲤科鱼类最多，有26种，占总种数的43．3％；其次为觥科，有11种，占总种数的18．3％。瑞丽江鱼类区系以喜温的“第三纪类群”中的山区鱼类为主要成分，上游杂有耐高寒的“青藏高原类群”成分，下游杂有热带江河平原鱼类。从生境、生活水层及食性探讨了瑞丽江鱼类生活史特点，并简要分析了鱼类的受危因素并提出了相应的保护建议。

英文摘要：

Field survey of fishes in Ruili River drainage has taken place for three times respectively in September of 2003; April and November of 2006. A total of 49 species were collected including one new species Microrasbora microphthalma, which the genus Microrasbora was first recorded in China. By Combination of the investigated species and specimens in the museum of Kunming Institute of Zoology, the Chinese Academy of Sciences （KIZ）, there are a total of 60 species belonging to 8 orders, 19 families and 44 genera in Ruili River drainage, among which 16species are endemic to Irrawaddy drainage and 9 species are introduced. On composition the species of Cyprinidae are dominant, which have 26 species accounting for 43.3 % of the total number of species. In the next place, Sisoridae has 11 species, accounting for 18.3 % of the total. The Fish fauna are major composed of ＂the later Tertiary group＂ fishes which habituated to live in hill - streams. However, the upper streams of Ruili River mix with some ＂Qinghai-Tibetan plateau group＂ fishes which can stand against extreme cold conditions, and the lower streams contain fishes which preferring to live in warm conditions of tropic plain rivers. This paper discussed the characters of life history about fishes from their aspects of habitats, aqueous layer and feeding habits. We also briefly analyzed the threatened factors and put forward some corresponding conservation suggestions.