Tilapia culture is an increasingly important sector in the Mekong Delta and Vietnam generally. To contribute to promotion of tilapia culture in the region, two experiments were conducted at the College of Aquaculture and Fisheries. The first experiment was designed with at different salinities (0, 5, 10, 15 and 20ppt) without or with biofloc (C:N ratio of 20:1) for each salinity treatment. The second experiment was conducted with bioflocs at different C:N ratios (10:1, 15:1, 20:1, 25:1 and control) at salinity of 10ppt. Mono-sex GIFT tilapia (initial size of 1.38 g and 4.4cm)  were stocked at 40 fish/m³ in 0.5-m³ composite tanks and each treatment was triplicate.  Bioflocs was created by adding rice flour as carbon source. Pellet feed were given daily at 5-10% of fish BW. After 5 months of culture, the first experiment showed water quality parameters (temperature, pH, TAN and nitrite) in the normal ranges for fish culture. Especially, TAN levels in the biofloc treatments were significantly lower than those of the treatment without bioflocs (p0.05). For the second experiment different C:N ratios, after 4 month of culture, the highest growth rate of fish was obtained at treatments C/N: 25/1 and 20/1 (average 208g and 21.5cm). The floc volume in the treatments C/N: 20/1 and 25/1 are significantly higher than those in other treatments (p) (32,6 and 41,2ml/L). Survival rates among treatments were not significantly different among treatments (p>0.05). The findings of this study strongly recommend for further development of tilapia culture in brackish water area (10-20ppt), applying bioflocs technology, especially in the Mekong Delta where has great potential for the industry.