Elevated liver and skin tumor prevalence has been reported in brown bullhead(Ameiurus nebulosus) from the tidal Anacostia River, Washington, D.C. Movement data areneeded to effectively use tumor prevalence as an indicator of habitat quality. We used ultrasonictelemetry to verify the residency of 40 adult brown bullheads (250–310 mm total length) in theAnacostia River during summer 2000, spring 2001, and fall–winter 2001–2002. During summer(10 fish tagged), fish remained within 500 m of their capture–release location, and their mean95% minimum area polygon (MAP) and linear home ranges were 4.5 ha and 0.50 km. Duringspring (12 fish tagged), most fish traveled upstream of the capture–release location as watertemperatures increased; they were approximately 1 km upriver by the end of the season. Mean95% MAP and linear home ranges in spring were 19.7 ha and 2.1 km. During fall–winter (18 fishtagged), fish released in the river remained within 4.2 km upstream and 3.1 km downstream oftheir capture– release location, and their mean 95% MAP and linear home ranges were 15.9 haand 2.1 km. In comparison, the 95% MAP and linear home ranges of fish released in LakeKingman (a tidal freshwater impoundment of the Anacostia) were 5.8 ha and 0.58 km. No fishwere located outside of the Anacostia River. We conclude that adult brown bullheads wereresident in the system throughout the year.