Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.
Gobio gobio is a cyprinid fish widely distributed across Europe and possibly through Asia. Introduced populations have become established in Norway, Ireland, Italy, Spain, Portugal, and Morocco, mostly for reasons related to angling. No introductions have yet been reported in the United States, but within the contiguous U.S., climate match is high. Introduced populations are often characterized by high abundance; the only negative impact reported is localized extinction of Romanogobio benacensis (formerly recognized as Gobio benacensis) in Italy. The mechanism of the displacement of R. benacensis by G. gobio has not been explained. The overall risk assessment category for G. gobio is high with medium certainty because of the continuing questions surrounding distribution and impacts of this species.