Pesticides are major environmental pollutants that are now widely distributed in aquatic environments and affect non-target organisms. Besides,they not only cause changes in foodweb chains by disrupting food chains, but also cause inconsistencies and imbalances throughout the whole ecosystem. The entry of pollutants into the aquatic environment can lead to the loss of planktonic and zooplankton populations or go thorough the food chains over the higher nutritional levels such as fish that make up the human diet,which may risk human health.In this study, the effects of different densities of malachite green on growth, survival and reproductive parameters of two species of Daphnia magna and Ceriodaphnia quadrangula of cladoceran were evaluated. Experiments as a randomized design were done for C. quadrangula during 21 days and for D. magna in the 19-day period at 21 °C.Cladocera were fed using algae Scenedesmus quadricauda and Chlorella vulgaris . In this experiment, zooplankton were evaluated with five concentrations of malachite green (0, 0.1, 0.3, 0.5 and 0.8 mg/l) in three replicates.The results showed that different concentrations of malachite green had a significant effect on the amount of moulting, survival rate, population density, specific growth and doubling time in C. quadrangula (P 0.05).The most frequent moult, the highest number of neonates, the highest specific growth and the lowest doubling time of the C. quadrangula population with 28.7 times in the whole period, 87.7 (neonates) in the total period, 4.4in the day and 0.7 days in the 0 concentration were obtained.Different concentrations of malachite green had a significant effect on moulting, survival rate, population density and duplication time in D. magna (P 0.05).The highest number of moult and the highest specific growth were observed in the D. magna population with 27.7 times in the whole period and 2.8 in the day at 0 concentrations.According to the results, it can be said that malachite green is toxic for the studied species and causes a disturbance to the reproductive system and growth of D. magna and C. quadrangula . Keywords : Daphnia magna , Ceriodaphnia quadrangula , Cladocera, fungicide, molting, growth