The goal of this study was to investigate the effects of Nile tilapia and striped mullet fry stocking on the water quality of unfertilized fish farm using water quality index (WQI) method and zooplankton diversity index. Samplings were undertaken from pond 12 from one sample point over a 20- day period. The results indicate that, fry stocking showed detectable changes in the zooplankton assemblages. However, small differences in some limnological variables were noticed. Soon after the fry stocking, rotifers which constituted more than 90% of total zooplankton community
were replaced by Copepoda and Cladocera. To qualify the fish farm water, two indices were applied. Water quality (WQI) and zooplankton diversity indices were the same in appreciation. Diversity Index classified the pond water as being among moderately and heavily polluted, whereas the WQI demonstrated it as among medium and bad. It is suggested that Observation of the fish farm is necessary for proper Administration. Application of the WQI is also suggested as a very useful tool that enables the public and decision-makers to estimate water quality of fish farms.