Four species of minnows, i.e. Hemiculter leucisculus, H.bleekeri, Toxabram-is swinhonis, and Acanthobrama simoni, are most common and often occur in large populations in the fish-farming reservoirs in North China. It was found out in this work that these fishes should be considered as undesirable because of their slow growth, low production efficiency, and competition upon food against the cultured fishes and netting is an effective way to control the population of the minnows,as these fishes all shoal dens...