The time of zooplankton passage through the gut of tench larvae and their food selectivity was studied on days 17 and 22 of tench larvae life. The gut passage was assessed with a marker method. The marker were Artemia nauplii. In the larvae aged 17 days food passage took 5 h and in larvae aged 22 days-7 h. In the initial period of life the larvae were fed small species of Cladocera and Rotatoria. Later in the zooplankton sample spined rotifers were abundant. For this reason they were not willingly consumed by the larvae. In both zooplankton samples copepod nauplii were less abundant and they were not eaten by the larvae. The low gut fullness was found for both groups. It indicated the low consumption, larvae transferred from tanks with Artemia to tanks with zooplankton. Presumably the larvae were stressed during the manipulation. In this case the gut passage was assessed under conditions of low content of food organisms in the gut of larvae.