WWW.WAS.ORG • WORLD AQUACULTURE • JUNE 2024 49 (CONTINUED ON PAGE 50) on (Shumo et al. 2019). Some commonly used substrates such as manure and kitchen waste may not provide enough minerals for the larvae (Alfiko et al. 2022, Table 1). Another key challenge is bioavailability of the minerals in BSFL-based diets. Even though the rearing substrates or the BSFL themselves contains minerals, they might not be readily available for absorption due to limiting factors such as the mineral form and interactions with other components (Ojha et al. 2021). Minerals can exist in different forms, where some are more easily absorbed by fish than others. Some feed components such as phytate, which is commonly found in plant-based ingredients, may hinder mineral absorption by binding to minerals such as calcium and zinc to produce complex compounds that cannot be absorbed by aquatic species (Lall and Kaushik 2021). Moreover, mineral bioavailability can be affected by processing methods used on BSFL meal, such as drying and grinding. These methods may change the physical or chemical structure of minerals, affecting their solubility and absorption by fish (Ojha et al. 2021, Figure 2). Mineral requirements differ by fish species, and also depending on their life stage, growth rate, and physiological needs. For example, fast-growing fish like salmon require more calcium than slower-growing species like catfish (NRC 2011). Raw BSFL, with potentially inconsistent mineral content, may not meet the various needs of different fish species effectively for properly formulated, mineral-fortified aquafeed. To address these limitations and ensure BSFL provide a nutritionally complete diet for aquatic species, mineral fortification emerges as a powerful tool to maximize the potential of BSFL-based aquafeeds. Mineral Fortification Strategies for BSFL aquafeeds To realize the full potential of incorporating Black Soldier Fly Larvae (BSFL) in aquafeeds, it is essential to explore fortification methods that can effectively enhance the nutritional composition of BSFL-based feeds, while ensuring they meet the specific dietary requirements of target aquatic species. The use of fortification strategies to enrich aquafeeds with essential minerals can ensure optimal fish health and growth. Researchers from the International Centre of Insect Physiology and Ecology (ICIPE, Figure 4) are currently working to address potential mineral deficiencies in Black Soldier Fly Larvae (BSFL), offering diverse approaches. Several key strategies that incorporate various approaches to addressing potential mineral deficiencies in BSFL-based feeds are highlighted below. Direct Inclusion This method involves adding pre-mixed mineral supplements directly into the aquafeed during the processing stage. This makes it possible to precisely regulate the types and quantities of minerals added, ensuring the final feed product satisfies the specific FIGURE 2. BSFL meal is becoming increasingly available for use in animal feeds.
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