Effects of different carbon sources on water quality, biofloc quality, and the productivity of Nile tilapia reared in biofloc-based ponds

The present study evaluated the effects of different carbohydrates materials used as carbon sources on water quality, biofloc quality, and growth and productive performance of Nile tilapia (Oreochromis niloticus) reared in biofloc (BFT)-based cement ponds (25 m x 10 m x 1.2 m; with 250 m³ volume). Nile tilapia fingerlings (44.9±1.9 g) were distributed into nine ponds at a density of 40 fish per 1 m³ (10000 fish/pond) to represent three treatments in triplicates. The control ponds received no carbon source addition; meanwhile sugarcane molasses (MO) and wheat flour (WF) were added to ponds. A commercial diet (30% crude protein) was offered to fish in each pond at levels of 3% and 2% of live body weight of fish in the control and BFT-based ponds, respectively, for 12 weeks. The amounts of feed were divided equally to three equal portions and offered to fish at 9:00, 13:00, and 17:00 h. The control ponds’ water was replaced by 50% every day with new water; meanwhile in MO and WF ponds, water loss via evaporation or leakage was compensated to reach the 1.0 m depth only. The pH value as well as unionized ammonia and nitrite levels, in the present study, were significantly lower, meanwhile nitrate and total suspended solids levels were significantly higher in MO and WF-treated ponds than the control one. The WF treatment resulted in significantly larger biofloc volume and higher total bacterial count compared to the MO treatment. The highest growth and production indices of Nile tilapia were observed in the BFT-based treatments as compared with the control group; particularly at the WF treatment followed by the MO treatment. In conclusion, the WF addition to cement fishponds is a more beneficial carbonaceous source for the efficient water quality, biofloc biomass, and growth and productivity of Nile tilapia reared in BFT-based system.