Although not Federally listed as threatened or endangered, the roundtail chub, also a sportfish in Arizona, is nearly extirpated from sections of the Verde and Salt river drainages. The purpose of this investigation, from March 1998 through March 2000, was to describe ecological requirements and population dynamics of roundtail chub. The objectives were to describe species composition, distribution and abundance, quantify habitat selection by different life stages, estimate population size, quantify movement and age and growth, and describe the reproductive capacity of roundtail chub.