Abstract:
BioFloc Technology (BFT) is based on in-situ microorganisms that recycle nutrition by
assimilating the toxic nitrogenous waste to improve the water quality in aquaculture
facility. This study was conducted to identify the effects of locally available Carbon (C)
sources on water quality management and growth of Guppy (Poecilia reticulata)
fingerlings in a BFT system. Six BFT treatments with three C sources were checked as
Rice Bran (RB), Molasses (MOL), Wheat Flour (WF), 1:1 mix of RB: MOL (RBMOL),
1:1 mix of WF: MOL (WFMOL), and 1:1 mix of RB: WF (RBWF). Control (CON) was
maintained without any carbon source. Male Guppy fish (0.25 ± 0.02 g and 2.23 ± 0.09
cm) were cultured in fiber-reinforced plastic tanks (30 fish/80 L tank) for 42-days and
fed with a commercial diet (3 % BW/day) once a day. C/N ratio was maintained at 15:1
by adding relevant carbon sources. Growth performance and feed utilization of fish and
water quality (Temperature, DO, pH, Ammonia, Nitrite and Nitrate) were evaluated. Feed
Conversion Ratio in all the BFT treatments (0.99±0.08 to 1.31±0.18) were significantly
lower than that of CON (2.27 ± 0.41). The final weight of fish in all BFT treatments were
significantly higher than CON (0.46±0.09 g) except for MOL (0.56 ± 0.10 g). RBWF
(0.74±0.14) and RB (0.71±0.13) treatments showed significantly higher weights than the
MOL. The final length of fish in RB (3.07±0.22 cm), RBWF (3.02±0.19 cm) and WF
(2.97±0.27 cm) were significantly higher than the CON (2.75±0.24 cm) and MOL
(2.76±0.19 cm). Percentage Average Daily Gain and %Specific Growth Rates of RBWF
(4.66±0.23 and 2.58±0.08) and RB (4.60±0.49 and 2.56±0.16) treatments were
significantly higher than CON (1.64±0.43 and 1.24±0.25). Survival rates were between
42% (RB) and 69% (RBWF). Temperature (27.87 0C), DO (7.72 mg/L), and pH (7.81)
were within the favorable range. Total Ammonia Nitrogen (TAN) levels of all the
treatments were below 1.09 mg/L without any significant differences with CON. Nitrite
levels of BFT treatments were lower than 0.53 mg/L. The use of BFT systems with a 1:1
mix of Rice Bran: Wheat Flour (RBWF) as the carbon source has increased the growth
performance, survival, feed utilization, and floc quality in terms of inhabited
microorganisms of Guppy reared in biofloc system. Therefore, it can be concluded that
1:1 RBWF mixture is the best carbon mixture among the tested carbon sources for
maintaining BFT systems for Guppy culture tanks.
