The six main stem Missouri River reservoirs are described, and information available through 1964 on plankton, water chemistry, fish populations, and water management is discussed. At maximum pool, these reservoirs have a capacity of 76 million acre-feet and a surface area of 1.2 million acres. Each of the upper reservoirs is larger in capacity and area than the sum of the lower three reservoirs. Fishes common in this system are bigmouth buffalo, carp, river carpsucker, yellow perch, goldeye, northern pike, sauger, walleye, white crappie, black crappie, and freshwater drum. Available information on growth rates, year-class strength, and relative abundance of common species is described. Limiting factors of the environments are the turbidities, wind, and fine soils. Research needs and problems relative to fish production are discussed.