Aquaculture in arid and dry locations must focus on utilising as little freshwater as possible due to a scarcity of freshwater resources. Agricultural-aquaculture integration is an excellent alternative technique for lowering nutrient discharge levels, reducing water consumption, increasing profitability, and transforming fish culture wastewater into valuable products. The current study used a solar energy system to operate two separate Integrated Multi-Trophic Aquaculture (IMTA)/Aquaponics systems (Nutrient Film Technique, NFT, and Floating Raft Systems, FRS) to cultivate Nile tilapia, African catfish, thin-lipped grey mullet, freshwater prawns, freshwater mussels, and a variety of vegetables. The tilapia and catfish were fed only commercial diets and all wastewater from the ponds, including dissolved and solid substances, was delivered sequentially to ponds with other cultured species. Water then flows through the IMTA system’s terminal point to the NFT and FRS systems, and returned to the tilapia and catfish ponds. The total biomass gain for aquatic species in the IMTA system was 736.46 kg, compared to 145.49 and 271.01 kg in the tilapia and catfish monoculture systems, respectively. The IMTA system had a cumulative feed conversion ratio (FCR) of 0.90, compared to 1.28 and 1.42, for tilapia and catfish monoculture systems, respectively. Nile tilapia and catfish consumed a total of 571.90 kg of feed, with nitrogen (N) and phosphorous (P) contents of 25.70 and 9.70 kg, respectively, and gained 11.41 and 3.93 kg of dietary N and P, representing 44.40 and 40.46% of dietary N and P retention, respectively. The addition of mullet and prawns to the system increased dietary N and P utilization efficiency to 59.06 and 51.19%, respectively, and the addition of mussels enhanced N and P efficiency to 65.61 and 54.67%, respectively. Finally, the incorporation of FRS and NFT systems raised dietary N and P efficiency to 83.51% N and 96.82% P, and 74.29% N and 79.81% P, respectively. These findings suggest that IMTA, as a bio-integrated food production system, may convert the majority of fish-fed residue into useful products and that this technology is suitable for food production in desert, rural, and urban areas in developing countries.
Keywords: Integrated Multi-Trophic Aquaculture, Nutrient Film Technique, Floating Raft System, nutrient cycling, mullet, freshwater prawn, freshwater mussels, catfish, tilapia