Effect of biofloc technology on growth, digestive enzyme activity, hematology, and immune response of genetically improved farmed tilapia (Oreochromis niloticus)

Abstract

Abstract An 8-week experiment was conducted to investigate the effects of biofloc technology (BFT) on the growth, digestive activity, hematology, and immune response of genetically improved farmed tilapia (GIFT) in light-limited and zero-water exchange culture tanks. The experiment consisted of one BFT treatment and a control group with water exchange. Glucose was added to the BFT treatment to establish a carbon/nitrogen (C/N) ratio of 15. The stocking density was 3 kg m− 3 in each 500-L indoor tank. Nitrite and nitrate concentrations were significantly lower in the BFT treatment than in the control (P 0.05), but the serum glutathione peroxidase and lysozyme activities were considerably higher in the BFT treatment than in the control fish (P Statement of relevance To date, preliminary studies based around the concept of the biofloc technology (BFT) were focused mainly on shrimp culture, and few studies have been conducted on fish in such systems. In addition, BFT have documented mainly the water quality, growth and production performance of tilapia systems. However, little is known about the effect of BFT on the physiological health of fish particularly concerning digestive enzyme activity, hematology as well as the immune response, which are very important in aquaculture. Therefore, the aim of the present study was conducted to investigate the effects of BFT on the growth, digestive enzyme activity, hematology, and immune response of genetically improved farmed tilapia (GIFT) in light-limited and zero-water exchange culture tanks. The monitoring indicated that BFT had beneficial effects on the maintenance of good water quality, improvement of feed utilization, and the growth performance of GIFT compared with the control group. The crude lipid content of BFT fish exhibited an increasing trend. Furthermore, BFT improved the digestive enzyme activity of GIFT. Although there were no significant differences in the hematological parameters of GIFT, BFT had a positive effect on the immune response of cultured tilapia. According to this study, it is suitable for rearing GIFT in such a light-limited indoor BFT system. BFT may be a promising alternative technology for a conventional clear water system operated with water exchange in cultivating both herbivorous and omnivorous fish species including tilapias. In addition, the significance of the present study may offer a potential practical approach for disease prevention and health management in fish aquaculture.