The aim of this study was to determine the prevalence peak of the smallest plankters that are an adequate food resource for vendace (Coregonus albula L.) larvae. This goal was accomplished by determining weekly changes in zooplankton biomass, especially rotifers and nauplii, against changes in basic physicochemical parameters of lake waters. As the results of this paper show, the highest abundance of the smallest plankters, rotifers and nauplii, occurs at a particular temperature for a period of two weeks. The most important variable that determined the peak of small plankter biomass is temperature. Thus, the period of stocking lakes with vendace larvae should be synchronized with this temperature and the coinciding biomass peak of rotifers and nauplii, which are the basic food of vendace larvae.