Effects of different protein levels and carbon sources on water quality, antioxidant status and performance of common carp (Cyprinus carpio) juveniles raised in biofloc based system

Abstract An 8 weeks trial was performed to evaluate the effects of crud protein (CP) levels (20 and 30%) each in three carbon sources in BFT (sugarcane molasses: M, rice bran: R, M + R and control) on water quality and performance of Common carp (cyprinus carpio) juveniles. Seven hundred twenty healthy juveniles (30.5 ± 3.1 g) were randomly distributed in 24 rectangle tanks (200 L) at a density of 4.5 kg m−3 (30 fish/tank). Juveniles in BFT treatments were fed at 75% of the daily feeding rate (DFI) of control. At the end of the experiment, the results showed that among the BFT treatments, M + R in both CP level had the lowest amount of total ammonia nitrogen (TAN) in comparison with other carbon sources in CP levels. The 30% CP level and rice bran contained treatments (R, R + M) significantly increased weight gain, specific growth rate (SGR) and survival and decreased feed conversion ratio (FCR) when compared the M and control treatments (P