Distribution of the orangefin madtom (Noturus gilberti) was determined from 347 sites sampled in Virginia and North Carolina. This species inhabited 264 stream kilometers, over twice the reported range, in the following systems: Craig Creek, Roanoke River, Dan River, Big Chestnut Creek, South Mayo River, Pigg River, and Smith River. The orangefin madtom was somewhat common; 33% (Dan River) to 70% (Craig Creek) of the sites sampled were occupied. Negative interspecific associates of orangefin madtoms included chubs, mountain redbelly dace, rosyside dace, crescent shiners, and crayfish; only Roanoke darters were considered positive associates. Sand and silt levels were significantly lower at sites with N. gilberti, while percentage of small cobble, local gradient, and depth were significantly higher. Discriminant function analysis identified large gravel, local gradient, silt, and occurrence of rosyside dace and crayfish, as significant predictors of the occurrence of the orangefin madtom. Seasonal samples from Craig Creek consisted of three age groups. The smallest individual captured was 33 mm total length (TL) and the largest was 111 mm TL. Mortality appeared moderate from age I until summer of the third year, when most individuals apparently died shortly after spawning. Spawning habitat of orangefin madtoms in Craig Creek appeared to be fast-water riffles dominated by small cobble substrate. Attempts to induce N. gilberti spawning in the laboratory were unsuccessful due to high mortality of captive fish. Field-collected margined madtom egg masses, however, were successfully hatched, and subsequent survival was significantly greater for fry fed ground trout chow versus live brine shrimp nauplii. / Master of Science