The Chinese mitten crab Eriocheir sinensis is listed in The Global Invasive Species Database and the IUCN Register as one of “100 of the world’s worst invasive alien species”. It has been reported in Serbia since 1995 in the Danube River, suggesting a predominantly human-aided dispersal. The risk of invasiveness posed by the Chinese mitten crab to aquatic ecosystems in Serbia, assessed using the FI-ISK (Freshwater Invertebrate Invasiveness Scoring Kit, v1.19), revealed a final score of 37. This shows a high potential of invasiveness, mainly due to its versatile ecological and biological features in a climate similar to that in the donor area. FI-ISK assessment revealed the alleged environmental impact of Chinese mitten crab in Serbia to be of much greater impact on aquaculture than previously assumed