Performance Efficiency of Selected Medium Culture and Raft Systems for Waste Removal in a Small-Scale Aquaponics Production System

Abstract

Aquaponics systems integrate aquaculture and hydroponics to create a sustainable method for food production by recycling nutrients. However, nutrient waste management in aquaponics systems remains a challenge, particularly in achieving optimal growth for both fish and plants while minimizing environmental impacts. This study compared the effectiveness of raft and selected medium culture systems in removing waste from a small-scale aquaponics production system that included leafy vegetable crops (Brassica oleracea) and Nile tilapia (Oreochromis niloticus). The aquaponics systems comprised of four hydroponics systems: three media based (charcoal, perlite, and pumice) and one raft system in a completely randomized design. The crops were cultivated in the hydroponic units, while O. niloticus fingerlings were reared in the fish tanks for 22 weeks. To compare the various hydroponics systems, growth metrics for the fish (weight and length) and plants growth parameters such as leaf index and biomass, as well as nutrient analysis were monitored and documented. Physicochemical parameters of the culture water were also monitored. Fish grown in the perlite medium had significantly higher mean final length and weight compared to other aquaponics setups in the study (p < 0.05). Plants grown on pumice had significantly more total biomass than other media (p < 0.05) and had the highest crude protein (CP) content, while those planted on perlite had the highest crude lipid content (p < 0.05). The charcoal medium was the most effective, lowering total ammonia nitrogen (TAN) levels by up to 67.1%. Pumice showed the highest total suspended solids (TSSs) retention capacity (p < 0.05), resulting in a 25.9% drop in TSS levels. The raft system was the least effective at reducing aquaculture nutrient waste. This study demonstrated that the choice of hydroponics media is important in optimizing aquaponics systems for both plant and fish growth.