Abstract

Aquaponics is the combined culture of fish and plants in recirculating systems. IntegratinRag fish and plant culture offers several advantages. Dissolved waste nutrients are recovered by the plants, reducing discharge to the environment and extending water use. The concentrated solid waste that is discharged can be used for associated land agriculture. A secondary plant crop, which receives most of its required nutrients at no cost, improves system profit potential. The plants purify the culture water and eliminate the need for separate and expensive biofilters. Savings are also realized by sharing operational and infrastructural costs. In addition, the intensive production of fish and plants reduces land requirements. Aquaponic systems do require a high capital investment, moderate energy inputs and skilled management. Niche markets may be required for profitability. In response to the need for more food fish and plant crop production in small Caribbean islands, an outdoor commercial aquaponic system was developed for the production of tilapia and leaf lettuce. It consists of fish rearing, solids removal and hydroponic components which utilize diffused aeration, solids removal, nitrification and direct nitrogen uptake by plants to maintain water quality. Annual average production during a 2.5-year trial was 3.1 mt of tilapia and 1,248 cases of lettuce on 0.04 ha of land. This system represents an intermediate technology that is ecologically stable and allows sustainable weekly harvests of fish and plants. The system is being modified with the goal of increasing production lo 5.0 mt of tilapia and 1,700 cases of lettuce. In light of recent findings indicating that 24°C water temperature assures optimum lettuce production, two methods of regulating water temperature (chillers and evaporative cooling towers) will be investigated. Additional research will be conducted to determine the culture potential of other species such as ornamental fish, vegetables (e.g., tomatoes), culinary herbs, medicinal plants and cut flowers.

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