ABSTRACT: The Indo-Pacific lionfish Pterois volitans has invaded western Atlantic Ocean coastal habitats over the past 2 decades and has the potential to cause major ecological changes in reef fish communities. While many aspects of lionfish ecology in their invaded range have been examined, there is a paucity of information on movements of lionfish, particularly adults. We surgically implanted ultrasonic transmitters into 25 lionfish at a natural hard bottom area off North Carolina (USA) in December 2008 and February 2009, and used an array of remote underwater receivers to monitor movements in the study area for up to 6 mo. We also affixed a control transmitter in the study area to assess changes in transmitter detection rate as a function of multiple variables, and used a generalized additive model to show that the control transmitter detection rate declined with time, increasing water temperature, and increasing wave period. Despite variable detection probabilities, we found that telemetered lionfish remaining in the study area displayed high site fidelity to areas no broader than 400 m in diameter; daily movements were nearly always <150 m. By estimating variable detection rates of transmitters and lionfish movements, we provided information that can be useful in understanding the spatial scale of lionfish impact and developing management or mitigation strategies for this invasive species.