Ecological Risk Screening Summary - Walking Catfish (Clarias batrachus) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally and are of establishment concern for the contiguous United States based on a climate matching analysis.

Clarias batrachus, walking catfish, is a fish that is native to southeastern Asia. They inhabit lowland streams, swamps, pond ditches, canals and stagnant water. They are hardy fish that can survive in waters with low oxygen and are facultative air breathers, making them the ideal inhabitants of areas with limited water. C. batrachus are an important food source that is marketed, as well as one that is used in aquaculture and aquarium trade. This species has been introduced through aquaculture and ornamental trade and established nonnative populations in many countries, including the United States. Of note, it has been introduced to and become established in thermally regulated waters in Turkey. Clarias batrachus has been documented to invade aquaculture facilities and eat large numbers of stock fish in Florida and have been detrimental to native fish species in Sri Lanka and the Philippines. The History of Invasiveness for Clarias batrachus is classified as High. The climate matching analysis for the contiguous United States indicates establishment concern for this species. Florida, where they are established, had high climate match for C. batrachus. There are also areas of high climate match along the southern Atlantic and Gulf Coasts. The Certainty of Assessment for this ERSS is classified as Medium due to conflicting information regarding the native range of the species and gaps in representing of the range in the climate matching analysis. General biological and ecological information as well as records of introduction and impact were available. The Overall Risk Assessment Category for Clarias batrachus in the contiguous United States is High.