Recirculating Aquaponics for Tilapia-Prawn-Vegetable Polyculture

The system was governed by the principle of “one-pump rule” where culture water was recirculated by a 40-watt pump in a closed loop. The design prevented the system from failure and collapse since only one pump lifted the water from the bio-filtration tank, the lowest section, to the fish tank, the highest section, and allowing water to flow by gravity along the raceway and return pipe network and back to the bio-filtration tank. The system generated good water quality having 5.6 parts per million average dissolved oxygen at 100 per cent average saturation and 21.4°C average temperature with 7.1?7.5 pH and 250?390 parts per million total dissolved solids. After a 108-day growing season, 71 pieces of Nile tilapia weighing 22 kilograms and 208 heads of freshwater prawn weighing 1.137 kilograms were recovered while 500 pieces of vegetables with 180 kilograms salable weight were harvested. The system consumed 5,225 liters of water which included 10 per cent evaporation losses. The system was able to utilize and added more value to limited resources such as water, electricity and space by producing more food in one system and structure.