Evaluation of the condition of balance between fishes and available fish foods in impoundments of multispecies fish culture in Taiwan was made by analyzing the quantitative interrelations between the standing crop of fish food biota and the stocked fishes of ecologically different species in a 6 hectare pond with organic fertilization and feeding, and 99 irrigation reservoirs with a total water surface area of 697 hectares. Ina balanced condition, the growth rate of plankton, macrophytes, benthos and neckton kept pace with the rate of consumption by the fishes, respectively of several species within the impoundment. Studies the interaction between the fishes and the fish food biota in the two types of impoundments with different management methods. These studies provide a basis for improved management of impoundments.