Ecological Risk Screening Summary - Tawes (Barbonymus gonionotus) - Uncertain Risk

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

Tawes (Barbonymus gonionotus) is a species of cyprinid native to river drainages in southeastern Asia. It will enter flooded forests during the wet season. B. gonionotus is a food fish that is raised in aquaculture and also wild caught. The species has been used for vegetation control in reservoirs. The history of invasiveness is not documented. There were many records of introductions found. A few records of ‘harmful’ impacts were found but no details were provided; no scientifically defensible studies could be found that concluded this species had harmful impacts after an introduction and establishment. One source recorded competition between this species and native co-geners but did not indicate the impact this competition has on the native species. Another source documented that the importation, culture, and establishment of this species has had a beneficial economic impact. However, Pallewatta et al. (2003) stated that this species is suspected as the most likely vector for introducing epizootic ulcerative syndrome to Bangladesh, causing wide spread fish mortality. This disease is on the 2017 list of OIE reportable diseases. B. gonionotus has been shown to have the ability to control populations of Najas and Ceratophyllum in areas where they have been introduced for that purpose. Those species are native to the United States and could be significantly impacted if B. gonionotus were to establish a population. The climate match is low; the Climate 6 score was 0.000, low. Southern Texas and Florida had areas of medium climate match. The certainty of assessment is medium. The overall risk assessment category is uncertain.