Exploring the impact of black soldier fly larvae (Diptera: Stratiomyidae) meal produced on different substrates in diets for Nile Tilapia and Channel Catfish fingerlings

ABSTRACT Objective This study evaluated black soldier fly Hermetia illucens larvae (BSFL) meals produced on two different substrates—the Gainesville housefly Musca domestica diet (Gainesville diet [GD]) or brewery waste (BW)—as partial or complete replacements for menhaden fish meal in the diets of Nile Tilapia Oreochromis niloticus and Channel Catfish Ictalurus punctatus. Methods The nutritional profiles of the BSFL meals produced on the two different substrates were analyzed and found to be significantly influenced by the production substrates. Next, two separate feeding trials were concurrently conducted in which two sets of isonitrogenous (40% and 35%) and isolipidic (13% and 10%) experimental diets were formulated for Nile Tilapia and Channel Catfish, respectively. Diets for both species were composed of practical ingredients to contain 0, 10, or 20% of BSFL-BW or BSFL-GD on a dry-matter basis to replace 0, 50, or 100% of menhaden fish meal in each reference diet. Groups of 10 Nile Tilapia and 12 Channel Catfish juveniles (each initially averaging ∼8 g/fish) were stocked per species into each of fifteen 38-L aquaria operated as a recirculating system and were fed the experimental diets at a fixed percentage of body weight for 8 weeks. Results For both fish species, groups that were fed BSFL-BW- and BSFL-GD-based diets had significantly higher weight gain (16% for tilapia; 12% for catfish) and nutrient utilization parameters compared with those fed the reference diets containing menhaden fish meal. Carcass composition of both fish species fed the experimental diets showed decreasing moisture (1–2%) and increasing lipid (5–41% for tilapia; 10–34% for catfish) as the levels of BSFL meal increased in the diet depending on the substrate used (BW or the GD). Conclusions Either BSFL-BW meal or BSFL-GD meal could be included in diets for Nile Tilapia and Channel Catfish at 20% to completely replace menhaden fish meal without having any adverse effects on weight gain, feed utilization, or body composition of fingerling Nile Tilapia or Channel Catfish.