Tropical production of tilapia ( Sarotherodon aurea) and tomatoes ( Lycopersicon esculentum) in a small-scale recirculating water system

Abstract

An integrated fish and hydroponic tomato production system was evaluated for use in the US Virgin Islands. The system was constructed from readily available materials, and designed to minimize capital costs, energy and water use, and the technological skill needed for operation. Tilapia ( Sarotherodon aurea) and tomatoes ( Lycopersicon esculentum) were cultured outdoors for 181 days in a closed system containing 7.34 m 3 of water. Water quality suitable for fish production was maintained by aeration, biological filtration, sedimentation, hydroponic vegetable production and the addition of make-up water. Fish metabolites, wasted feed, and small quantities of inorganic fertilizers served as nutrient sources for tomato production. Fish survival (97.5%) and growth (2.54 g per day) were excellent with 63.6 kg of fish averaging 521 g each recovered at harvest. The total yield of ripe tomato fruit was 87.0 kg, of which 87.4% was marketable. The yield and quality of fruit produced hydroponically exceeded that produced under field trial conditions. Capital costs for the complete system were estimated to be US$612 (1979). Electrical energy and water use were 9.12 kWh day −1 and 2.6% of the total volume per day, respectively. Cost and return projections indicate the system could be operated on a profitable basis in the US Virgin Islands.