Design and Performance of an Indigenous Water Recirculating Aquaculture System for Intensive Production of Nile Tilapia, Oreochromis niloticus (L.), in Saudi Arabia

The increasing demand for fish, and the scarcity of fresh water in Saudi Arabia both press the need to adapt new technologies for intensive water recirculating aquaculture to maximize water recycling and increase fish production.Using locally available materials, a commercial-scale recirculating aquaculture system was developed in triplicate to produce Nile tilapia.The system was operated to produce more than 50 kg fish/ m 3 /cycle, and the filters were evaluated for their efficiency in removing organic wastes from the effluent.Each replicate consisted of a culture tank, two mechanical filters with sand/gravel medium, two submerged biofilters with plastic media, a sump and two pumps.Mixed sex tilapia with an average size of 76.4 g were stocked at a density of 188 fish/m 3 and fed a 34% protein diet at 3% body weight per day (initially).Water temperature was maintained at 28 ± 1ºC, water flow rate was adjusted to 300 liters/min and the culture tank and biofilter were aerated.Water