Three predator-dependent trophic functions have been fitted to experimental data on individual ration of two phytophagous rotifers (Brachionus calyciflorus and Philodina acuticornis) in laboratory monocultures of microalgae (Chlorella vulgaris Beyer, Scenedesmus quadricauda Brev. and Synechocistis sp.). The best fit was obtained with theoretical dependence proposed in that generalises the Arditi-Ginzburg ratio-dependent trophic function, approaching the Holling type II expression when either predator or prey density becomes low. At the same time the obtained results suggest that the original ratio-dependent function of Arditi-Ginzburg can be effectively used for modelling trophic interactions in the considered systems, because individual ration of rotifers is determined by the ratio of microalgae to consumer abundances.