In the present study, the effect of different carbon sources on water quality and growth performance of common carp (Cyprinus carpio) fingerlings by adding synbiotic into biofloc system (BFT) were investigated for 45 days. Three experimental treatments (B, C and D) containing corn, wheat and barley flours together with a control group (A) were prepared. The used synbiotic was a mixture of Bacillus circulans and B. lichiformis along with a Celmanax liquid commercial prebiotic at a final concentration of 1.5×10⁸ CFU/ml to each treatment. Fish fingerling (15.98±1.93 g) was distributed randomly into 12 tanks (4 treatments × 3 riplicated) with 30 liters of capacity. At the end of the experiment, the nitrate, total hardness and total suspended solidsin in all treatments significantly increased compared with the control (P<0.05). While, the dissolved oxygen in all treatments was lower than the control (P<0.05). NO₃ was measured higher than the control only in corn and barley treatments (P<0.05). The highest final weight (40.31±11.20 g), SGR (1.59±0.27%), TGC (0.98±0.09%), condition factor (2.21±0.17), FCE (106.09±29.47%), PER (4.71±1.31), PEL (18.22±5.04) and PEE (0.13±0.04) were recorded in corn flour treatment. However, the lowest feed conversion ratio (1.01±0.25) and relative feed intake (11.94±3.79%) were observed in corn flour treatment (P<0.05). The highest excretion rates of ammonia (1011.45±14.27 mg.kg^-1BW.day^-1), urea (25.30±3.57 mg.kg^-1BW.day^-1) and energy wast by excretion rates of ammonia (25.36±3.50 mg.kg^-1BW.day^-1) and urea (6.21±0.78 mg.kg^-1BW.day^-1) were recorded in barley flour (P<0.05). In conclusion, the results demonstrat that the use of corn flour with synbiotic in the BFT system, compared to other carbon sources was more effective to improve the water quality and promoting of growth preformance of common carp fingerlings.