Asian swamp eel, Monopterus albus/javanensis [Zuiew, 1973/Lacepede, 1800], has been established in the southeastern USA since at least 1994, yet little is known about its ability to survive low winter temperatures. We use standard thermal methodologies to quantify low-temperature responses and provide a detailed description of swamp eel reactions to cold temperatures. When exposed to chronic temperature decreases of 1.0 C per day, swamp eels ceased foraging at 15.0 C, markedly diminished movements below 11.0 C, and became incapacitated near 9.6 C. During critical thermal minima (CTmin) trials, swamp eels exposed to acute temperature drops (0.25 C per minute) tolerated temperatures as low as 6.2 C. Swamp eels exhibited a moderate cold acclimation response, gaining 0.23 C in cold tolerance for every 1 C drop in acclimation temperature. Progressive time-series CTmin estimates for eels acclimated to 20.5°C followed by an acute temperature decrease to 16.0 C, revealed that cold acclimation may occur in only 8 days.