Effect of Black soldier fly larvae (BSFL) dietary inclusion on Ecosystem services and NPK use efficiency of Aquaponics systems with Tilapia and Spinach

Abstract

Aquaponics is a sustainable food production system that combines aquaculture and hydroponics in a symbiotic relationship. However, one of the challenges of aquaponics is to find a suitable and affordable feed source for the fish. Black soldier fly larvae (BSFL) are an alternative feed source that can be produced from organic waste and have high nutritional value for fish. BSFL can also provide ecosystem services such as waste reduction, nutrient recycling, and pest control. The aim of this study was to evaluate the effect of BSFL dietary inclusion on the ecosystem services and NPK use efficiency of aquaponics systems with Nile tilapia (Oreochromis niloticus) and spinach (Spinacia oleracea). Five experimental diets were formulated with different levels of BSFL inclusion: Control (0% BSFL), TA (10% BSFL), TB (20% BSFL), TC (30% BSFL), TD (40% BSFL), and TE (50% BSFL). The experiment was conducted for 35 days in a recirculating aquaponics system with six fish tanks and six plant beds. The fish growth performance, water quality parameters, plant biomass, NPK content, and waste reduction were measured and compared among the treatments. The results showed that TC had the best fish growth performance, with the highest weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. The water quality parameters were within the acceptable ranges for both fish and plants in all treatments. The plant biomass and NPK content were highest in H, followed by Control, TC and TB. The waste reduction was also highest in TD, followed by TC and TE. The NPK use efficiency was calculated as the ratio of NPK uptake by plants to NPK input by fish feed. The results showed that TD had the highest NPK use efficiency, followed by TC and TB. The study concluded that BSFL dietary inclusion can improve the ecosystem services and NPK use efficiency of aquaponics systems with tilapia and spinach, with 40% BSFL being the optimal level.