The body-scale relation, calculated length, length-weight relation, age at maturity, and sex ratio of 13 major species collected in Lake Oahe from 1963 to 1968 with trap nets and bottom trawls are described. Eight species grew at a faster rate than has been recorded in other Missouri River reservoirs: goldeye (Hiodon alosoides), bigmouth buffalo (Ictiobus cyprinellus), smallmouth buffalo (Ictiobus bubalus), white bass (Morone chrysops), black crappie (Pomoxis nigromaculatus), white crappie (Pomoxis annularis), walleye (Stizostedion vitreum vitreum), and freshwater drum (Aplodinotus grunniens). Four species grew at rates similar to those recorded from other Missouri River reservoirs: carp (Cyprinus carpio), yellow perch (Perca flavescens), northern pike (Esox lucius), and sauger (Stizostedion canadense). One species -- river carpsucker (Carpiodes carpio) -- grew slower than in other waters. Growth generally was excellent for all major species in the early years of impoundment (1959-62) but then declined. Species showing the greatest decline in growth from 1962 to 1967 were goldeye, bigmouth buffalo, sauger, walleye, northern pike, and freshwater drum. As growth rate decreased, age at sexual maturity increased for northern pike, carp, river carpsucker, bigmouth buffalo, and freshwater drum. Although inundation of new lands was associated with rapid growth of fishes in the early years of impoundment, water level fluctuations during the growing season had no discernible effect on growth rate. Increased average reservoir depth, which decreased the amount of littoral area, was associated with decreased fish growth.