Nutrient Film Technique (NFT) Aquaponics Enhances the Productivity of Fish and Crops: Trials on Nile Tilapia, African Catfish, Lettuce, Spinach and Basil

Abstract

This study investigated the efficiency of nutrient film technique (NFT) aquaponic systems in enhancing the productivity of Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus), and leafy vegetables (lettuce, spinach and basil) under aquaponic conditions. The study was conducted for 9 weeks at the Maseno University Fish Farm in Kenya. Identical tilapia-based and Catfish-based NFT setups were used, whereas soil-based crop cultivation and earthen fishpond systems served as controls. Mono-sex male tilapia and catfish fingerlings were stocked at an initial average length of 10 cm and weight of 50 g. The fish were stocked at a density of 60 fish/m3 and fed to satiation on a 35% crude protein formulated diet twice a day, whereas crops were transplanted after being raised for 20 days in the nursery and when they had at least three fully developed leaves. Fish growth in the NFT system was significantly better than in pond-based systems for tilapia and catfish. Tilapia achieved a final weight of 175 g and a feed conversion ratio (FCR) of 1.44 in NFT, compared to a final weight of 129.86 g and an FCR of 2.1 in the pond-based system. Catfish had a significantly higher total yield in the earthen pond (15.4 kg/m3) than in the NFT system (12.5 kg/m3) (p < 0.05). Lettuce had significantly higher leaf area (179.9 cm2) and final yield (36 kg/m2) compared to spinach with leaf area (85.2 cm2) and yield (30.2 kg/m2), and basil with leaf area (38.0 cm2) and yield (5.7 kg/m2). The Tilapia NFT system demonstrated superior performance for fish and vegetable growth, performance and yield, water and nutrient use efficiency, and nitrogen recovery. This better performance is due to the better nutrient profile of tilapia waste compared to catfish and better adaptability to NFT systems compared to catfish.