Nile tilapia(Oreochromis niloticus)is one of the most widespread invasive fish species,which have successfully established populations in the major rivers of Guangdong Province,China.To investigate the biomass of Nile tilapia and assess its impact on fisheries and native species,field surveys and manipulative experiments were conducted.Nile tilapia was largely found on each site,especially on Meihua and Huazhou.We also found that the increase of Nile tilapia in these rivers not only affect the CPUE of fish community and native fish species but also reduce the income of fishers.In the manipulative experiments,we found that the growth of native mud carp was decreased when Nile tilapia was added.Our results suggested that invasion of Nile tilapia negatively affected fishery economy as well as native fish species and suitable control measurements should be taken.