Abstract: The study was conducted in Batyaghata sub-districts, Khulna, Bangladesh to observe how three different components of rice, duck and fish in a polyculture system are benefited from each other. The study was conducted in a land size of 0.087 ha, which was divided into two parts measuring 0.058 and 0.029 ha. In the larger part (0.058 ha) ducks and fishes were introduced along with rice. Rice and fishes were cultured in the rest of the land. Four fish species namely, Rohu (Labeo ruhita), Catla (Catla catla), Mirror carp (Cyprinus carpio) and Nilotica (Oreochromis niloticus) were introduced in both parts of the land with a stocking density of 1800, 2700, 1500 and 2100 fry ha-1 respectively. No additional feed was supplied for the fishes. Thirty ducks of Zending breed were allowed to graze in the larger part of the land. There were four male ducks and the rests were female. The ducks were allowed to graze during the daytime and they were confined in a house constructed on the corner of the land. The yield of rice was 690 kg ha-1 where it was cultivated with ducks and fishes and 1450 kg ha-1 where it was cultivated with fishes only. The possible reason of such unexpected results might be due to over grazing of ducks soon after the rice was transplanted. During the study period (3.5 months) the fish production was 1.23 and 0.91 t ha-1 for rice-fish-duck polyculture and rice-fish culture systems respectively. The egg production percentage of ducks was 61.21. The analysis of variance in respect of culture systems showed that the growth performances of Rohu, Catla and Mirror carp were highly significant (P<0.001). Therefore, the duck dropping was found very effective for better growth and development of fishes