Threats at home? Assessing the potential ecological impacts and risks of commonly traded pet fishes

Invasive alien species (IAS) are major drivers of global biodiversity loss, and the poorly regulated international pet trade is a source emerging future invaders. Predictions likely ecological impacts risks such IAS have been significantly enhanced in recent years with new metrics, which require application to many more actual potential IAS. Hence, this study assesses two readily available species: goldfish, Carassius auratus , non-native populations worldwide; white cloud mountain minnow, Tanichthys albonubes limited invasion history date. First, we compared per capita feeding rates these European trophically analogous natives – stone loach, Barbatula barbatula common Phoxinus phoxinus using Comparative Functional Response method. Second, used foraging experiments conspecific pairs determine synergistic, neutral or antagonistic intraspecific interactions. Third, performed novel object assess boldness, known “dispersal enhancing trait”. Goldfish had highest maximum four species, while minnows lowest. Neutral interactions were observed for all paired experiments, goldfish having consumption demonstrated greater being active during experimental trials approach than minnows. Further, combining rates, boldness availabilities from our survey shops, assessed relative (RIR) non-natives. This highlighted as higher risk most worthy management prioritisation, mirroring its extensive history. We propose that metrics direct policy decisions towards ever-increasing biological invasions worldwide.