Productivity of polycultured nile tilapia (Oreochromis niloticus) and pacific white shrimp (Litopenaeus vannamei) in a recirculating system

Two experiments were conducted in the Environmental Research Laboratory of the University of Arizona in Tucson, AZ, USA, to evaluate the production of Pacific white shrimp (Litopenaeus vannamei) and Nile tilapia (Oreochromis niloticus) in recirculating polyculture and monoculture systems. The experiments were conducted for six weeks in twenty and sixteen 200-l fiberglass tanks, respectively, at a salinity of 10 ppt. In the first experiment, tilapia were fed pelleted feed at 3%, 2.25%, or 1.5% of their body weight. In the second experiment, tilapia were stocked at 12, 8, or 4 fish/cage, submerged in the shrimp tanks. In general, total production of fish and shrimp was higher in polyculture than in monoculture. The better growth of shrimp in polyculture appears to be because shrimp were able to utilize waste from the tilapia. In experiment 1, shrimp growth did not significantly differ between treatments (p>0.05) but tilapia growth was rapid, with significant differences between treatments; higher feeding rates produced higher biomasses. In experiment 2, growth significantly differed between shrimp grown in polyculture with 12 fish/cage and shrimp grown in monoculture. Final mean shrimp weights averaged 10.83±0.97, 10.37±0.96, and 10.20±0.94 g in polyculture, but only 9.85±0.73 in monoculture while tilapia growth did not significantly differ between treatments. This study shows that adding Nile tilapia to shrimp tanks at suitable stocking densities and appropriate feeding rates produces positive interactions.