In the present study, Moina macrocopa were grew at four different densities (4, 20, 40 and 80 individuals/50 mL), to investigate the effect of population density on the growth and reproduction using aquaculture effluent throughout 11 days. The organisms in high population densities i.e. 40 and 80 ind./50 mL of aquaculture effluent showed a lower rate of reproduction and population growth compared to those at 4 and 20 ind./50 mL. In the lower densities, Moina population increased to the highest densities of 55 (4 ind./50 mL) and 61 individuals (20 ind./50 mL) at the first 5 and 10 days, respectively. In general, two lower densities showed a higher population increment compared to other two tested densities. These results suggest that high population density suppressed the growth in M. macrocopa, therefore, lower population densities are recommended for commercial hatchery production using aquaculture effluent.