This review provides a contemporary account of knowledge on aspects of introductions of non‐native fish species and includes issues associated with introduction pathways, ecological and economic impacts, risk assessments, management options and impact of climate change. It offers guidance to reconcile the increasing demands of certain stakeholders to diversify their activities using non‐native fishes with the long‐term sustainability of native aquatic biodiversity. The rate at which non‐native freshwater fishes have been introduced worldwide has doubled in the space of 30 years, with the principal motives being aquaculture (39%) and improvement of wild stocks (17%). Economic activity is the principal driver of human‐mediated non‐native fish introductions, including the globalization of fish culture, whereby the production of the African cichlid tilapia is seven times higher in Asia than in most areas of Africa, and Chile is responsible for c. 30% of the world's farmed salmon, all based on introduced species. Consequently, these economic benefits need balancing against the detrimental environmental, social and economic effects of introduced non‐native fishes. There are several major ecological effects associated with non‐native fish introductions, including predation, habitat degradation, increased competition for resources, hybridization and disease transmission. Consideration of these aspects in isolation, however, is rarely sufficient to adequately characterize the overall ecological effect of an introduced species. Regarding the management of introduced non‐native fish, pre‐introduction screening tools, such as the fish invasiveness scoring kit (FISK), can be used to ensure that species are not introduced, which may develop invasive populations. Following the introduction of non‐native fish that do develop invasive populations, management responses are typified by either a remediation or a mitigation response, although these are often difficult and expensive to implement, and may have limited effectiveness.

Biological invasions are responsible, in addition to significant biodiversity declines, for enormous economic losses to society as well as monetary expenditures for their management 1,2 . The InvaCost database has allowed for the first time a reliable, comprehensive, standardized, and easily updatable synthesis of the monetary impacts of invasions worldwide 3 . Here, we found that total reported costs of invasions reached a minimum of $1.288 trillion (2017 US dollars) over the last few decades , with an annual average cost of $26.8 billion. Moreover, we estimate that the annual average cost could reach $162.7 billion in 2017. These costs remain massively underestimated and do not show any sign of slowing down with a consistent three-fold increase per decade. Our synthesis reveals that documented costs are both widely distributed and with strong gaps at regional and taxonomic scales, with damage costs being an order of magnitude higher than management expenditures. Research approaches for documenting costs of biological invasions need to be further improved. Nonetheless, our findings are a compelling call for the implementation of consistent management actions and international policy agreements aiming to reduce invasive alien species burden.