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The 2025 Journal of Fish Diseases paper Insect Larvae Meal as a Complementary Functional Ingredient in High Soybean Meal-Based Diets Improve the Health of Rainbow Trout (Oncorhynchus mykiss) is useful because it avoids the usual framing trap. Jie Ma and colleagues did not ask whether black soldier fly larvae meal can simply replace a large share of fishmeal. They tested whether low levels of BSFL can help a soybean meal-based diet perform better under health pressure.
That is exactly the kind of question the BSF sector needs more often.
The trial compared six diets: a fishmeal control, a soybean meal-based diet, and soybean meal-based diets supplemented with 2.5% or 5% whole-body BSFL or 2.5% or 5% defatted BSFL. The challenge organism was Flavobacterium psychrophilum, a relevant pathogen for salmonids. The reported outcomes included gut health, immune response, survival after bacterial challenge, lauric acid deposition and intestinal morphology.
The important result is not the inclusion level. It is the use case
The paper reported that BSFL inclusion positively influenced gut health, immune response and survival following F. psychrophilum challenge compared with the soybean meal diet. The strongest survival signal was observed in the 5% whole-body BSFL group. Dietary lauric acid also translated into higher whole-body lauric acid levels in a dose-dependent pattern in fish fed BSFL diets.
Histology pointed in the same direction. BSFL-fed fish showed improved intestinal morphology, especially in the absence of pathogenic enteritis. Gene expression after challenge included upregulated pro-inflammatory markers such as IL-8, TNF-alpha and C5, which the authors interpret as an enhanced immune response.
For formulators, this is not a story about maximum insect inclusion. It is a story about making a high-soy diet less fragile.
That distinction has commercial weight. Soybean meal is economically important in aquafeed, but high inclusion can create digestive and inflammatory constraints depending on species, life stage, processing and total diet design. A low-dose animal-derived ingredient that helps maintain gut structure and disease response in that context has a different value proposition from a bulk protein ingredient.
Whole-body versus defatted matters
The strongest survival result being associated with 5% whole-body BSFL is commercially interesting. Defatting can improve protein concentration and formulation flexibility, but it also changes the product. If part of the functional signal is linked to lipids, lauric acid or other fat-associated compounds, then defatted and whole-body meals should not be treated as interchangeable.
This is a recurring problem in insect ingredient marketing. “BSF meal” is often discussed as one product. It is not. Whole-body meal, partially defatted meal, heavily defatted meal, oil, hydrolysate and chitin-rich fractions may occupy different formulation slots. Ma et al. reinforce that point because the study design separates whole-body and defatted products at the same inclusion levels.
For BSF producers, this argues for product segmentation rather than a single generic meal. If whole-body BSFL produces a stronger health signal in a specific high-soy trout diet, that does not automatically mean whole-body meal is always better. It means the residual lipid and associated bioactives deserve attention as part of the specification.
The strategic implication for BSF producers
The paper’s conclusion is unusually aligned with a practical commercial strategy: reposition BSFL as a functional feed ingredient instead of only as a fishmeal replacer. That matters because low inclusion can reduce the two biggest barriers to aquafeed adoption: cost and supply volume.
At 2.5% to 5%, a feed mill can trial BSFL without rebuilding the entire protein matrix. The producer can defend value through performance under stress rather than commodity protein price. The market size is also more realistic for the insect sector’s current production capacity. Replacing large shares of fishmeal across aquaculture is a volume challenge. Supplying functional inclusions to targeted diets is a more plausible near-term route.
The paper also suggests where BSF has the clearest early fit: diets that are already economical but biologically stretched. High-soy salmonid feeds are a good example. The buyer does not need a story about insects saving the planet. The buyer needs a controlled ingredient that improves fish health outcomes in a formulation that already makes economic sense.
What should come next
For commercial use, the study should lead to replication rather than overclaiming. The most valuable next trials would test different soybean meal levels, different trout life stages, longer grow-out windows, alternative pathogen models, and field-relevant feed manufacturing conditions. It would also be useful to separate which part of whole-body BSFL drove the response: lipid fraction, lauric acid, peptide fraction, chitin, microbial-associated compounds, or a combined matrix effect.
The immediate lesson is already strong. Low inclusion BSF can be more than a compromise. In the right diet, it can be a functional support ingredient that helps plant-heavy aquafeeds perform with less biological penalty.
That is a much better sales position than asking nutritionists to believe in high fishmeal replacement before the product has earned its place.
Sources
- Jie Ma, Krishna Pada Singha, Mosope F. Abanikannda, Veronica Myrsell, Nicholas Romano, Elizabeth A. Koutsos, Daniel Adams, Kenneth D. Cain and Vikas Kumar. Insect Larvae Meal as a Complementary Functional Ingredient in High Soybean Meal-Based Diets Improve the Health of Rainbow Trout (Oncorhynchus mykiss). Journal of Fish Diseases, 2025, 48(12). DOI: 10.1111/jfd.14153.
- PubMed record: PMID 40620170.
