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A 75-day rearing trial was completed to investigate the effectiveness of different biofloc systems (BFT) on the water quality, growth performance and health status of Florida red tilapia (FRT) grown in brackish groundwater (BGW). The trial consisted of the control and three types of BFT using different carbon sources (CS), starch (ST), rice bran (RB), and wheat bran (WB) in triplicate, expressed as BF-0, BF-ST, BF-RB, and BF-WB, respectively. Fish weighing 4.98 ± 0.01 g/fish were stocked in 250-L tanks at an initial stocking density of 25 fish. The findings demonstrated significant reductions in inorganic nitrogen by-product (NH3 and NO2) levels in all BFT groups compared to the control, with an increase in floc volume and floc nutritional value, in the BF-ST and BF-RB groups. Furthermore, fish in the BF-ST and BF-RB groups showed significant improvements in fish growth indices (final weight, weight gain, and FCR). Fish in the BFT groups showed significant improvement in kidney function indices and plasma lipids with no significant changes in liver enzyme activity compared to the control. Lower stress markers (glucose and cortisol) and higher digestive enzyme activity (lipase and protease), innate immune parameters and antioxidants were reported in fish of the BF-ST and BF-RB groups compared to the control fish. Histopathological inspection revealed that the BF-ST fish exhibited healthier livers and shared healthier intestines with BF-RB fish compared to the control group. In conclusion, RB is an appropriate CS with BGW for desert aquaculture due to its availability, inexpensiveness, and comparable outcomes with ST. [ABSTRACT FROM AUTHOR]

Freshwater scarcity poses challenges to aquaculture worldwide, including countries like Egypt. In this study, we investigate the feasibility of integrating underground saline water (USW) with varying salinities into a Biofloc (BFT) system for desert mariculture of Florida red tilapia (FRT) and its impacts on water quality, fish performance and health. Four BFT treatments (C/N ratio = 15) were examined in triplicate using four salinity levels 0 ppt, 12 ppt, 24 ppt and 36 ppt, expressed as S0, S12, S24 and S36, respectively. For 75 days, a total of 12 fiberglass tanks (each 250 L−1 water) were used to store FRT fry (average weight of 1.73 ± 0.01 g/fish). The fish were fed an experimental diet (protein/fat = 30/5) and an additional carbon source of rice bran. The results revealed that group S12 showed better growth indicators, higher survival rate, lower FCR, and lower ammonia levels, while group S0 exhibited lower growth indicators (final weight, weight gain, and specific growth rate) than all groups. The serum kidney, liver, and antioxidant indices performed better in the S12 group. At 12 ppt, the immune-related parameter (IgM) increased by 22.5%, while the stress parameter (cortisol) decreased by 40.8% compared to the S0 group. The liver and intestinal histopathological results revealed that the S12 and S24 groups performed better. Pathogenic bacterial load counts favored the S24 group, which had the lowest number among the groups studied. The recommended salinity for FRT cultivation in USW and BFT is 19.94-20 ppt, determined by polynomial regression of FW and FCR. [ABSTRACT FROM AUTHOR]