We evaluated critical current speeds (CCS, cm/s) for young Gulf (of Mexico) Coastwalleyes (Stizostedion vitreum) and compared the results to field determinations of water velocityunder different flood conditions in Luxapalila Creek, Mississippi, which supports a smallpopulation of this species. Critical current speeds for actively feeding walleyes ranged from 8 to74 cm/s, and were related to fish standard length (SL, mm) by log10(CCS) = -0.231 + 0.927 .log10(SL), for which P < 0.0001, r 2 = 0.67, and N = 83. Mean current velocities in Luxapalila Creekbetween May and June ranged from 20 to 45 cm/s. Means were higher than the CCS for a youngwalleye at that time, but velocities were spatially variable. Persistence of walleyes in LuxapalilaCreek and similar streams probably depends on the availability of instream structures that locallyreduce current speed. Removal of such structures or channelization of such streams couldcompromise the survival of a genetically unique southern population of walleye.