1. The introduction of non-native species is a major driver of biodiversity loss, posing a growing threat to the health and functioning of freshwater ecosystems globally. In recent decades, pet trade and aquarophilia have become lucrative industries, accelerating the introduction and spread of new non-native fishes. This includes several Asian loach species that have recently been detected outside their native range, such as in Europe, the United States and Australia. Here, we examine the potential of the large-scale loach Paramisgurnus dabryanus and the dojo weatherloach Misgurnus anguillicaudatus to establish outside their native range, and address potential impacts on the threatened European weatherfish Misgurnus fossilis.
2. We used species distribution models (SDM) to estimate the potential global environmental suitability for both Asian loach species and identified key variables determining current distributions.
3. Our results indicate that both species could spread globally and become invasive, with M. anguillicaudatus appearing more capable of larger range expansions compared to P. dabryanus. Especially temperate regions of Europe, North and South America, the south-eastern coast of Australia, and Asia were identified as the most vulnerable areas. Range expansions of both studied Asian loaches in Europe could lead to an increased distribution overlap with populations of the native M. fossilis, with projections showing P. dabryanus increasing from a current overlap of 0.1% to 4.1% and M. anguillicaudatus from 0.2% to 32.8%.
4. Our findings indicate that the introduction of non-native loaches may pose a substantial threat to M. fossilis in its native range, but also to other native species, especially benthic fish and macroinvertebrate species. Preventing new introductions and targeted research on the ecology and distribution patterns of such highly invasive species with growing presence in the international pet trade is essential to halt their further spread. SDMs can offer relevant spatial data for policymakers by identifying regions vulnerable to invasions and prioritising areas for targeted surveillance and management efforts.