Ecological Risk Screening Summary - Crucian Carp (Carassius carassius) - Uncertain Risk

Species that are considered uncertain risk need a more in-depth assessment beyond the Ecological Risk Screening Summary to better define the species’ risk to U.S. environments.

Carassius carassius, Crucian Carp, is a fish native to much of Europe and parts of Asia. It is tolerant of heat, cold, organic pollutants, and hypoxic conditions, and has established populations outside its native range in over a dozen countries. There have been a couple of reports of introductions to the contiguous United States, but there is doubt as to whether the species was correctly identified and no populations became established. C. carassius is morphologically similar to other Carassius species and known to hybridize with them as well as with common carp, Cyprinus carpio. The species is also documented as susceptible to at least two diseases listed by the World Organisation for Animal Health, along with numerous other parasites and pathogens. The History of Invasiveness for Carassius carassius is classified as Low due to multiple peer-reviewed studies from the United Kingdom finding no negative impacts of C. carassius introduction on invertebrate diversity, macrophyte presence, or amphibian populations. The climate matching analysis for the contiguous United States indicates establishment concern for this species. Most regions of the contiguous United States had a high climate match; low climate matches were found only in small areas of the Pacific Northwest and Southwest. The Certainty of Assessment for this ERSS is classified as Medium due to the history of misidentifications obscuring the true distribution of C. carassius and because all studies demonstrating no negative impacts of C. carassius introduction were done in a single country. The impacts of introduction of C. carassius have not been studied in many of its established locations. The Overall Risk Assessment Category for Carassius carassius in the contiguous United States is Uncertain.