Abstract: Biological invasions have caused the severe decrease of global bio2diversity and the destruction of global ecosystem.However, these events also offer newopportunities for species to evolve following with the alteration of select press.In this paper, the reproductive tactics of Ctenogobius giurinus in an invaded area, Lake Fuxian, and two original areas, Lake Chao and Dongting, were compared to investigate the changes associated with its invading to plateau lakes.A total of 447, 360 and 341 specimens were studied fromLake Fuxian (from February 2003 to January 2004), Lake Chao and Dongting (both from October 2003 to September 2004).Results showed that C.giurinus in Lake Fuxian spawned fromJuly to October, with the breeding duration of 4 months.But those in Lake Chao and Dongting both spawned fromJuly to August, their breeding duration being only 3 months.With the decrease in percentage of spawning individuals during breeding season, the invasive population of C.giurinus experienced the loss of concentrative spawning phenomenon which was a common trait of the two original populations.The mean individ2 ual fecundities of C.giurinus were 5516 ?470 g(Mean 盨D) in Lake Fuxian, 2667 ?14 g in Lake Chao and 7567 ?254 g in Lake Dongting respectively.And their mean relative fecundities were 2826.5 ?27.4, 3657.9 ?66.5 and 3592.2 ?160.5 granule/g respectively.For the relative fecundity, those of the two original populations were quite similar, and they were significantly higher than that of the invasive population, which suggested the decrease in reproductive investment of C.giurinus in Lake Fuxian.Compared with those of the original populations, the change in gonado-somatic index of C.giurinus in Lake Fuxian was characterized with the delay of the maturing of gonad and the terminating of spawning or sperm expelling.All the changes were analyzed with the water temperature, nutrient status and the release of natural enemy in the invaded area, Lake Fuxian.