Research Article: Environmental sustainability assessment of Nile tilapia (Oreochromis niloticus) breeding in biofloc system

Sustainable development aquaculture industry entails the expansion of environmentally friendly systems. The aim of this study was to evaluate the environmental aspects of biofloc technology system (BFT) in Nile Tilapia (Oreochromis niloticus) culture. This research was performed on two systems including, Biofloc and flow-through system (FTS). Each system had three replications and carried-out for six months and sampled at intervals of ۱۵ days. The density in each ۳۰m۳ pond was ۱۵۰۰ juveniles of Tilapia (۲۵ g b/w each). The studied parameters include fish weight, oxygen, temperature, ammonium, nitrite, pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS) of effluent, feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER), survival rate, and cost of culture. The results indicated that temperature, oxygen, nitrite, and ammonium were significant different (p<۰.۰۵) and lowest level of NO۳(۰.۰۰۴mg/L), NH۴ (۰.۰۰۲ mg/L) observed in BFT. There were significantly different between growth indices and all physiochemical factors except for pH, during the time. Effluent factors include BOD, COD and TDS in BFT were significantly lower than FTS (p<۰.۰۵). The quality of the effluent in BFT contained only ۵%of the food with the effluent and ۲۵% of the food reused in the food chain, while in flow-through, ۲۵-۳۰% of food discharged along with FTS. The water exchange rate in BFT was ۱.۵m۳/day(۵%/day) and in flow-through was ۳۰m۳/day (۰.۳ L/s). The cost of feeding in BFT was ۲۵% lower than FTS system. Therefore, the results revealed that BFT, in addition to water quality improvement, leads to less feed consumption, higher quality production, and less environmental pollution.

Keywords:

Sustainable Aquaculture , BFT , Flow through , Environmental Aspects , Pollution , Resource.