We studied the survivorship and reproduction of the cyclopoid Eucyclops serrulatus using four diet types: algae Chlorella vulgaris and Scenedesmus acutus separately and each together with the rotifer Brachionus havanaensis. We used equal biomass (3.9 mg C l-1) of C. vulgaris and S. acutus while B. havanaensis was offered at a density of 0.5 ind. ml-1. Regardless of the food type, the average lifespan of female E. serrulatus varied from 30 to 50 days, and those of males from 22 to 27 days. When Chlorella was offered alone as food, the female lifespan was 40% lower than when fed together with B. havanaensis. The number of nauplii per female (gross reproductive rate, GRR) was higher on Scenedesmus alone than on Chlorella alone or Chlorella and Scenedesmus offered with Brachionus. Thus, GRR was not significantly influenced by the presence of rotifer in mixed diet. Net reproductive rate (Ro) and the rate of population increase (r) were similar at all the four food types. This implies that the diet-related differences of GRR did not ultimately translate to the differences in Ro or r, due to the survivorship patterns of the adult females.