Aims of this experiment, to examined the effects of food density and water salinity on filtration rate of oyster (Crassostrea belcheri) for fundamental data on assessing the suitable use of oyster as an alternative of biofilter in wastewater from an intensive shrimp pond. From the experimentation showed that an average of filtration rate within 24 hours of both size of oysters at different food density were significantly different (p0.01). The Filtration rate of oysters were decreased with increasing the food density. The average of filtration rate of oysters when exposed to different water salinity were significantly different (p0.01). The decrease in filtration rate of oyster was correlated with water salinity. The average filtration rate of oyster was high at water salinity range 15-25 ppt for small size and 10-25 ppt for large size.