Sustainable aquaculture requires novel protein sources that reduce dependence on finite marine resources while improving fish health and production efficiency. Along with the potential to replace fishmeal, black soldier fly larvae (BSFL) host antimicrobial properties that may mitigate disease in farmed fish. Hybrid striped bass (HSB; Morone saxatilis × Morone chrysops) is an economically important carnivorous fish with high dietary protein requirements. HSB are susceptible to streptococcosis, a disease caused primarily by the zoonotic pathogen Streptococcus iniae. This bacterial infection imposes a global economic burden exceeding $150 million annually, highlighting the need for integrated nutritional and health management strategies.
Fingerling HSB underwent an 8-week feeding trial to evaluate BSFL meal reared on red drum, tuna, or a standard “Gainesville diet” (GV) substrate as a partial replacement (50% and 75%) for Special Select menhaden fishmeal included at 15% by weight in the control diet. Growth performance, feed conversion efficiency, whole-body proximate composition, survivability, and condition indices were assessed to determine the value of these substrate-specific BSFL meals as functional additives.
To evaluate the functional health benefits of BSFL inclusion, a series of pilot challenge trials was conducted to refine a reproducible disease model using a virulent strain of S. iniae (LSU 10-070). Juvenile HSB originating from the same spawn exhibited high susceptibility, with injection challenges resulting in up to 100% mortality. Typical clinical signs of streptococcosis in HSB include erratic swimming, corneal opacity, and cranial hemorrhaging. BSFL-fed and control HSB were challenged via immersion in a flow-through system to determine BSFL as a functional component of dietary inclusion for farmed fish. The findings of this study will be presented.