02/07/2026
【Dr.Fish Weekly Literature Insight】
# Black Soldier Fly Is Not a “Magic Feed”: The Wrong Ratio Can Turn an Eco-Friendly Ingredient into an Aquaculture Risk
In recent years, black soldier fly has become one of the most widely discussed alternative protein ingredients in aquaculture feed.
Black soldier fly larvae can grow on selected agricultural by-products and organic resources, converting low-value materials into insect protein, oil, and frass. From a circular economy perspective, this creates real potential to reduce organic waste, produce alternative protein, and lower dependence on fishmeal.
Black soldier fly larvae also contain relatively high levels of protein and several essential amino acids, which is why they are increasingly considered a possible fishmeal replacement.
However, this has also created a common misunderstanding:
If black soldier fly is high in protein and environmentally friendly, does that mean more is always better?
The answer is no.
The value of a feed ingredient cannot be judged only by its crude protein content. What truly determines the result is digestible protein, amino acid balance, fatty acid composition, palatability, chitin level, and the ability of different fish and shrimp species to utilise the ingredient.
Black soldier fly has strong potential, but it is not a “magic feed.”
When the ratio is wrong, even an environmentally friendly ingredient may suppress growth, reduce feed efficiency, and increase production risk.
# # Fishmeal Replacement Ratio
When discussing black soldier fly, it is important to distinguish between the fishmeal replacement rate and the actual inclusion level in the total diet.
“Replacing 30% of fishmeal” does not mean that black soldier fly meal makes up 30% of the complete feed.
It means that black soldier fly is used to replace 30% of the fishmeal, or fishmeal protein, originally included in the formulation.
For example, if a diet originally contains 20% fishmeal, replacing 30% of that fishmeal does not mean the final diet contains 30% black soldier fly meal.
The actual inclusion level depends on the original fishmeal level, the protein concentration of the black soldier fly ingredient, dietary energy, and the overall nutrient balance of the formulation.
Therefore, the effectiveness of black soldier fly cannot be evaluated by looking at a single percentage.
Several questions must be made clear:
How much fishmeal was replaced?
What percentage of the complete diet is black soldier fly?
Were protein and energy levels kept consistent?
Were essential amino acids and fatty acids rebalanced?
Current studies on fish and shrimp suggest that, under properly formulated conditions, replacing approximately 25% to 30% of fishmeal can maintain acceptable growth and feed utilisation in some species. Certain studies have also reported potential benefits for immunity or intestinal health.
However, the results are not always consistent.
Species, body size, production stage, basal diet, and black soldier fly quality can all affect the outcome.
Some aquatic animals can tolerate higher replacement levels, while others show reduced growth or poorer feed conversion as the replacement rate increases.
For this reason, 30% should not be treated as a universal standard.
It is a reference level that must still be validated through nutritional formulation and feeding trials.
# # The Double-Edged Nature of Chitin
One major difference between black soldier fly and fishmeal is the presence of chitin in the insect exoskeleton.
Chitin is not necessarily harmful.
At an appropriate level, chitin and its derivatives may stimulate certain immune responses, influence gut microbiota, and provide functional benefits.
However, chitin may also become one of the main limitations when black soldier fly is used at high levels.
When dietary chitin becomes excessive, it may interfere with the digestion and release of protein, fat, and other nutrients. It may also increase the digestive burden on the intestine and reduce overall nutrient utilisation.
Some fish and crustaceans possess a certain level of chitinase activity and can process limited amounts of chitin.
But being able to handle some chitin does not mean they can consume unlimited quantities.
As the replacement level of black soldier fly increases, chitin intake also rises. Once this exceeds the digestive and adaptive capacity of the animal, nutrient digestibility may decline, feed conversion may worsen, and growth may eventually be suppressed.
This is why a high protein value on the feed label does not guarantee that all of that protein can be fully utilised.
What matters is not only how much crude protein is present, but how much the fish or shrimp can actually digest and absorb.
# # Fish and Shrimp Cannot Use the Same Ratio
Different aquatic animals do not respond to black soldier fly in the same way.
Omnivorous fish usually have broader dietary adaptability and may tolerate alternative proteins more effectively.
Some studies on tilapia have shown that a certain proportion of fishmeal can be replaced by black soldier fly without significantly affecting growth, provided that the diet is nutritionally rebalanced.
However, the same replacement level cannot simply be applied to carnivorous fish.
Carnivorous species generally have greater requirements for high-quality animal protein, essential amino acids, palatability, and long-chain polyunsaturated fatty acids.
If fishmeal is reduced and black soldier fly is increased without reformulating the entire diet, growth and feed efficiency may be affected.
Shrimp also require a different formulation approach.
Although shrimp naturally consume animal matter containing chitin, they still require a complete balance of amino acids, fatty acids, cholesterol, phospholipids, minerals, and energy.
Some studies on Pacific white shrimp have shown that moderate replacement of fishmeal with black soldier fly can maintain growth and may improve certain intestinal and immune indicators.
However, as the replacement level increases, nutritional balance, digestive capacity, and long-term growth performance must still be carefully evaluated.
Black soldier fly can therefore be used in both fish and shrimp diets, but not at the same ratio and not with the same formulation logic.
# # What Black Soldier Fly Eats Determines What Fish and Shrimp Eventually Receive
The ability of black soldier fly to utilise various organic resources is one of its strongest advantages.
But the fact that black soldier fly can consume many materials does not mean that every material is suitable for producing feed-grade insects.
The substrate used to rear black soldier fly larvae directly affects the final protein, fat, mineral, fatty acid, and sanitary quality of the insect biomass.
Even when two products are both labelled as black soldier fly meal, significant differences may exist between producers, substrates, and production batches.
If substrate control is poor, risks may include pathogenic microorganisms, pesticide residues, mycotoxins, heavy metals, and other contaminants.
Black soldier fly can convert organic material into insect biomass, but it cannot automatically convert every unsafe substance into safe nutrition.
Some contaminants may be metabolised.
Some may be excreted.
Others may accumulate in the insect body.
Therefore, black soldier fly intended for commercial aquaculture feed must come from controlled production systems with stable substrate sources, contaminant testing, microbial control, batch nutrient analysis, and product traceability.
If the ingredient is inconsistent, the formulation will also become inconsistent.
If the formulation is inconsistent, growth and production performance will be difficult to maintain.
# # It Can Become a Major Protein Source, but Only with Strict Formulation
Black soldier fly is not limited to being a minor functional additive.
In suitable species and carefully formulated diets, it has the potential to become one of the major protein sources and replace a substantial portion of fishmeal.
However, using it at a high level requires more than simply exchanging fishmeal for insect meal.
Fishmeal has been widely used for decades not only because it is high in protein.
It generally offers good digestibility, a relatively complete essential amino acid profile, high palatability, and useful levels of fatty acids, minerals, and other nutritional components.
Black soldier fly is not a complete nutritional copy of fishmeal.
If fishmeal is substantially reduced, the formulation must be rebalanced with other protein sources, supplemental amino acids, suitable oils, vitamins, minerals, and other nutrients.
Otherwise, what is lost may not only be fishmeal.
The original nutritional structure of the entire diet may also be disrupted.
Commercial use of black soldier fly is therefore not about mixing insect meal into an existing feed.
It requires redesigning the full formulation according to the nutritional needs of the target fish or shrimp.
# # The Future May Depend on Compound Insect Proteins Rather Than a Single Insect Source
If the goal is only to reduce part of the fishmeal, black soldier fly already has considerable potential.
However, if the objective is to reduce fishmeal dependence much further, or to make insect protein a major animal protein source, relying on black soldier fly alone may still present limitations.
Different insect ingredients have different nutritional strengths.
Some offer better essential amino acid profiles.
Some contain more fat.
Some have stronger palatability.
Some contain less chitin.
Others provide different functional nutrients.
For this reason, the future may not lie in finding one “perfect insect” that fully copies fishmeal.
A more practical direction may be to combine multiple insect proteins with plant proteins, microbial proteins, algae, and precise amino acid supplementation to create a more complete protein system.
Compound insect protein does not simply mean mixing several insect meals together.
It should be formulated according to nutritional complementarity:
One ingredient may correct the amino acid limitations of another.
Different sources may reduce the chitin pressure from relying on one insect alone.
Palatability and digestibility may be improved.
Batch variation may be reduced.
Supply and price risks may be distributed.
Fishmeal is a highly concentrated ingredient with a complex nutritional profile.
Replacing it further is unlikely to depend on a simple one-to-one substitution with a single alternative ingredient.
In the long term, compound insect proteins may become one of the most practical pathways for reducing fishmeal dependence.
But whether one insect source or several are used, the final result still depends on scientific formulation and aquaculture validation.
# # Sustainability Cannot Replace Science
Black soldier fly has genuine circular economy value and may help aquaculture reduce its dependence on fishmeal.
However, sustainability only explains why the ingredient deserves to be studied.
It does not prove that the ingredient is suitable at every inclusion level.
The true value of any feed ingredient must ultimately be judged through growth performance, feed conversion ratio, digestibility, health status, product quality, cost, and long-term production stability.
When the ratio is appropriate, the formulation is complete, and the source is safe, black soldier fly can become a valuable alternative protein.
When only crude protein is considered and the replacement rate is increased blindly, chitin, nutritional imbalance, poor palatability, and ingredient inconsistency may turn an environmentally friendly ingredient into a new production risk.
Black soldier fly is not a magic feed.
It is a feed ingredient that must be understood, calculated, and used correctly.
Professional aquaculture does not adopt a new ingredient simply because it is popular.
It first asks:
Which fish or shrimp species is it suitable for?
At which production stage should it be used?
How much fishmeal can it replace?
Is the chitin level too high?
Has the formulation been nutritionally rebalanced?
Is long-term growth stable?
Is the ingredient source safe and traceable?
At the right ratio, black soldier fly can help aquaculture reduce fishmeal dependence.
At the wrong ratio, even a sustainable ingredient may suppress growth, reduce efficiency, and increase production costs.
The real objective of future aquaculture feed should not simply be to use less fishmeal.
It should be to reduce pressure on marine resources while still providing fish and shrimp with complete nutrition that they can truly digest, absorb, and utilise.
**References**
Gougbedji, A., Detilleux, J., Lalèyè, P. A., & Francis, F. (2022). Can insect meal replace fishmeal? A meta-analysis of the effects of black soldier fly on fish growth performances and nutritional values. *Animals, 12*(13), 1700.
Tippayadara, N., Dawood, M. A. O., Krutmuang, P., Hoseinifar, S. H., Doan, H. V., & Paolucci, M. (2021). Replacement of fish meal by black soldier fly (*Hermetia illucens*) larvae meal: Effects on growth, haematology, and skin mucus immunity of Nile tilapia, *Oreochromis niloticus*. *Animals, 11*(1), 193.
Chen, Y., et al. (2021). Evaluation of dietary black soldier fly larvae meal on growth performance, intestinal health, and susceptibility to *Vibrio parahaemolyticus* in Pacific white shrimp, *Litopenaeus vannamei*. *Frontiers in Marine Science, 8*, 706463.
Li, X., et al. (2022). Replacing dietary fish meal with defatted black soldier fly larvae meal affected growth, digestive physiology and muscle quality of juvenile largemouth bass. *Frontiers in Physiology, 13*, 855957.
Oteri, M., et al. (2021). Black soldier fly larvae meal as an alternative to fish meal for aquaculture feed. *Sustainability, 13*(10), 5447.
Yamamoto, F. Y., et al. (2022). Dietary fishmeal replacement by black soldier fly larvae meals produced from different substrates: Nutrient composition and performance in red drum. *Aquaculture*.
Radhakrishnan, G., et al. (2023). Evaluation of black soldier fly larvae meal as a functional feed ingredient in Atlantic salmon. *Frontiers in Aquaculture, 2*, 1239402.
Dîrvariu, L., et al. (2025). Feed sources for sustainable aquaculture: Black soldier fly meal and its effects on fish growth, feed efficiency, and product quality. *Fishes, 10*(9), 464.
Food and Agriculture Organization of the United Nations. (2024). *The Black Soldier Fly Revolution in Support of Waste Reduction, Food Security and Water Conservation*. FAO.
Author: Ryan Tan Hong Joo
RAS Eco-Tech Aquaculture Expert ｜ Dr.Fish Founder
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