Influence of dietary black soldier fly larvae meal on largemouth bass growth performance, nutrient cycling and elemental dynamics in aquaponics
The use of aquaculture feed ingredients based on wild fish capture is an ecological concern since it leads to natural habitat destruction and loss of biodiversity. Addressing this concern, black soldier fly larvae meal (BSFLM) has been suggested as a promising alternative ingredient to replace fish meal. To date, the advantages and disadvantages of BSFLM as an alternative ingredient for different aquaculture species have been extensively investigated. However, its impacts on closed aquaculture systems, like aquaponics, particularly on water quality, plant growth and elemental dynamics, have not been researched extensively. Therefore, a 56-day feeding trial on the substitution of conventional fish meal with BSFLM at inclusion rates of 5, 10 and 15% on the performance of Micropterus salmoides (18.58 ± 2.86 g) and aquaponic system was conducted. The results showed that fish weight gain and plant ( Lactuca sativa ) yield were optimal at the 5% inclusion level but decreased at the 10 and 15% levels of BSFLM inclusion in the diet. The latest water quality parameters led to a decrease in ammonia and phosphorus levels by 15% BSFLM in the diet. The macro-mineral (Ca, Mg, K) utilisation efficiency decreased with increasing BSFLM levels, while trace minerals (Zn, Cu, Fe) were more effectively utilised at 5% inclusion. Most LCA impact categories increased with increasing levels of BSFLM in diet, mainly caused by the electricity and water demand and composting-related nitrogen emissions of BSFLM production. Findings suggest that a moderate 5% BSFLM inclusion is optimal for aquaponic system performance.