SUMMARY. The diet and feeding habits of natural and cultured populations of Mesocyclops leuckarti were studied. Nauplii and copepodid stages I–III are herbivorous. Copepodid stages IV–V and adults preferentially preyed upon Ceriodaphnia and Diaphanosoma whereas Bosmina was not preyed upon. Rate of predation on Ceriodaphnia and newborn Artemia nauplii was higher between 15–22°C than between 22–27°C. Under starvation conditions, the survival time for males was shorter than for females.