This book assembles information on the fish fauna of South Dakota into a conveniently usable form. Ninety-three species are described with precise data on distribution and measurements. Additionally, this book attempts (1) to collect and identify published records of South Dakota fishes, (2) to present keys for the identification of fishes known or expected to occur in South Dakota, (3) to record original distributional data based on 137 fish collections taken throughout the state, (4) to solve some problems involving the systematic status of certain South Dakota species, (5) to clarify or extend information on the distribution of several species in the adjoining Plains area, and (6) to determine the geographic sources of origin of South Dakota fishes and to interpret routes of postglacial dispersal.