We studied the population growth of two rotifer (Brachionus calyciflorus and Brachionus rubens) and two cladoceran (Ceriodaphnia dubia and Moina macrocopa) species fed three diets (Chlorella vulgaris (Ch), Scenedesmus acutus (Sc) and yeast (Saccharomyces cerevisiae) (Y) in seven combinations (alone or mixed in equal proportions (on dry weight basis): Ch+Sc, Ch+Y, Sc+Y and Ch+Sc+Y).