We investigated the abundance of fish communities and alien Nile tilapia in the main rivers of Guangdong Province and conducted control experiments to assess the impacts of Nile tilapia. In this study,we asked the following questions: 1) does the abundance of Nile tilapia affect the catch-per-unit-per-effort (CPUE) of native fishes in different surveys and sites, 2) does the
increase of Nile tilapia affect the income of fishermen 3) does Nile tilapia invasion affect the growth of the native mud carp?