Current status and potential risks of established alien fish species in China

Alien fishes are regarded as one of the major causes of the decline of aquatic fauna and biodiversity. Up to now, more than 500 fish species have been introduced into China from other countries. However, nationwide documentation of the established alien fishes is still lacking and their ecological risk is unclear. We compiled a comprehensive inventory of the colonized alien fish species based on various sources, and then provided a summary of their potential ecological risk. The results indicated that 68 alien fish species (13.44%) have successfully established in the natural waters. These species belong to 12 orders and 29 families. Among them, 56 species (82.35%) were introduced for aquaculture purposes, 11 species (16.18%) were introduced for aquarium and one species (1.47%) was introduced for bio-control. Over 85% of the established fishes were introduced after the 1970s. Geographically, these species are native to 12 regions around the world. Eighteen species and two hybrid species are native to North America which is the most dominant donor. Among these species, 61 can live in freshwater, 41 species can live in brackish and 19 species can live in marine water. Although large number of species, high taxonomic diversity, intensive human activity, diverse geographical origins and high adaptability of non-native species may lead to the increase of invasion risk, previous research about invasive risk just focus on the general impact of aquaculture activities, invasiveness screening using semi-quantitative models and distribution prediction using species distribution models. Further studies will need to be conducted on comprehensive risk assessment, ecological interaction between non-native fish and new environment, on fish species, ecosystem, the impact of human activity and global change on non-native fish colonization.