Effect of salinity on carrying capacity of adult Nile tilapia Oreochromis niloticus L. in recirculating systems.

Effect of salinity on carrying capacity of a recirculation system for Nile tilapia, Oreochromis niloticus L.; production was assessed. Survival, growth and feed conversion ratio of adult Nile tilapia fed 30% crude protein diet for 88 days were measured at three different salinity levels (8, 15 and 25 g L−1) and two stocking densities (20 and 40 m−3) in three independent recirculating systems. Highest survival (98%) and a linear growth in net biomass ( P<0.01) was observed in both densities at 8 g L−1 and in 20 m−3 treatment at 15 g L−1. Highest net biomass growth was observed in the 40 m−3 stocking density treatment at 8 g L−1 salinity level ( P<0.05). Overall biomass growth was significantly affected by salinity indicating a decrease in Nile tilapia carrying capacity with increased salinity. About 11 000 kg ha−1 crop−1 of Nile tilapia can be obtained in recirculating systems at 8 g L−1 salinity, significantly higher than the net production at 15 g L−1 (5200 kg ha−1 crop−1) and 22 g L−1 (4425 kg ha−1 crop−1). [ABSTRACT FROM AUTHOR]