Asian Fish Tapeworm: The Most Successful Invasive Parasite in Freshwaters

The Asian fish tapeworm (AFT), Schyzocotyle acheilognathi, is a notorious and highly successful invasive parasite reported in a wide spectrum of freshwater fishes, and new reports of its spread continue to emerge. To date, no thorough review of its worldwide distribution and host associations is available. In the present work, we collected information from 651 articles up until 2017, from which we updated the number of the hosts to 312 fish species and 11 non-fish species, which is quite unusual among helminths. The AFT has spread to all but one continent (Antarctica). The highest number of records are from North America, followed by Asia and Europe. A key feature of its invasive success is its broad environmental tolerance. The AFT is a highly successful invasive parasite of freshwater fishes. We have updated the number of reported hosts of the AFT to 312 fish species and 11 non-fish hosts; the dominant hosts are cypriniform fishes, especially common carp and grass carp, and cyprinodontiform fishes. The AFT has spread to almost all continents with the highest number of records from North America, followed by Asia and Europe. The broad environmental tolerance (biotic and abiotic) of the AFT is a key factor in its success. The AFT represents a potential threat mainly for native endemic and ornamental fishes, and reports of its range expansion continue to emerge, especially in North America. Recently designed microsatellites are now available to assess the genetic variability and geographic origin of individual populations of the AFT.