BSFL as Fish Feed: Replacing Wild-Caught Fishmeal in Aquaculture

The Supply Problem Driving the Question

The case for BSFL in aquaculture feed is not primarily a cost story. It is a supply constraint story. Global fishmeal production has plateaued at approximately 4.5-5 million tonnes per year since the 2000s, bounded by the biomass of small pelagic fish (anchoveta, herring, menhaden) available to the rendering industry. Aquaculture demand for fish protein has grown from approximately 1 million tonnes of fishmeal equivalents per year in 1990 to over 3 million tonnes per year in 2020, and global aquaculture output is expanding at 5-6 percent per year (FAO The State of World Fisheries and Aquaculture 2022).

The consequence is that fishmeal prices are both elevated and volatile. When Peruvian anchovy fishing quota reductions occur (as happened in 2015-2016 and again in 2021-2022), fishmeal prices spike above 2,000 EUR per tonne. BSFL protein prices, supplied from a system based on food industry waste streams rather than ocean biomass, are not subject to these supply shocks. A feed compounder with BSFL contracts in their protein sourcing portfolio has a price hedge against fishmeal volatility, independent of whether BSFL beats fishmeal on price in calm market conditions.

BSFL was the first insect protein authorised for use in EU aquaculture feed: Regulation (EU) 2017/893 permitted insect-derived PAP in aquaculture compound feed as of July 2017, four years before the 2021 authorisation for poultry. This means the commercial trial base in aquaculture is deeper than in poultry. Protix has been supplying Skretting salmon feed operations since approximately 2019-2020. The Skretting-Protix trials are the most commercially significant data set in European BSFL aquaculture use.

This page covers what those trials show: where BSFL performs, at what inclusion rates, and what the limits are by species. The poultry comparison is handled separately. The wider context of BSFL as a closed-loop bioconversion system frames both markets together.

The Mechanism: BSFL Protein in Fish Digestion

The digestibility of a protein source in fish depends on the amino acid profile, the presence of anti-nutritional factors, and the physical form of the meal. For BSFL protein meal, the primary digestibility variable is chitin content. Chitin is the structural polysaccharide in the insect exoskeleton, and most fish species have limited chitinase enzyme production. At high inclusion rates, chitin acts as an insoluble fibre that dilutes the energy and protein density of the ration and may irritate intestinal epithelium. This is why defatted, mechanically processed BSFL meal with reduced chitin content is the commercial standard for aquaculture feed, not whole dried larvae.

The exception is tilapia (Oreochromis niloticus). Tilapia produces chitinase at meaningful levels, allowing it to digest chitin and extract additional energy from the insect exoskeleton fraction. This makes tilapia the most efficiently served species in BSFL aquaculture feed, with apparent protein digestibility (APD) values approaching those of fishmeal at higher inclusion rates. Commercial tilapia producers in Southeast Asia and East Africa were among the earliest adopters of BSFL protein meal for this reason.

For Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), the digestibility picture is more complex. Salmon are obligate carnivores with amino acid requirements and palatability preferences evolved for fish protein. Fishmeal contains specific amino acids, attractants (trimethylamine, inosine monophosphate), and omega-3 fatty acids that BSFL protein meal does not fully replicate. At low inclusion rates (below 25 percent of the protein fraction), these differences are managed through amino acid balancing and lipid supplementation. At higher inclusion rates, feed intake, palatability, and digestibility begin to diverge from the fishmeal control.

The fat fraction of BSFL is rich in lauric acid (a saturated medium-chain fatty acid) and low in long-chain polyunsaturated fatty acids, specifically EPA and DHA, which are the omega-3s required for salmon flesh quality. A feed formulation replacing fishmeal with BSFL meal must supplement EPA and DHA from an alternative source (fish oil, algal oil, or rapeseed oil blend) to maintain the fatty acid profile required for commercial salmon production. This is a formulation step, not a performance barrier, but it adds cost to the BSFL substitution calculation.

The Numbers: Digestibility, FCR, and Species Data

Apparent protein digestibility (APD) for BSFL protein meal in Atlantic salmon has been measured at 85-91 percent in published trials (Belforti et al. 2015; Dumas et al. 2018). Fishmeal APD in salmon is approximately 90-94 percent. The 3-9 percentage point gap is meaningful for a feed formulator: a 90 percent APD protein source requires 11 percent more protein inclusion to deliver equivalent digestible protein than a 99 percent APD source. In practice, feed compounders compensate by targeting digestible protein rather than crude protein in the formulation specification, which means BSFL inclusion rates are adjusted upward relative to the fishmeal inclusion they replace.

The Skretting-Protix salmon trials (Skretting technical reports 2020-2022, referenced in Protix company disclosures) tested defatted BSFL protein meal at 25 and 50 percent fishmeal replacement in Atlantic salmon grow-out diets over a 16-week trial period. Results at 25 percent replacement: no statistically significant difference in specific growth rate (SGR), feed conversion ratio (FCR), or condition factor. Results at 50 percent replacement: FCR within 5-8 percent of fishmeal control; SGR marginally reduced (approximately 3 percent). Flesh quality parameters (fillet colour, omega-3 content) maintained with supplemental fish oil at both inclusion levels. These are the commercially relevant numbers: 25 percent replacement is a straightforward substitution; 50 percent requires careful amino acid and fatty acid balancing but is technically achievable.

The 100 percent fishmeal replacement case does not work for salmon at current BSFL formulations. Full replacement reduces growth rate by 20-30 percent, largely attributed to palatability and the absence of fishmeal-specific attractants and micronutrients. This is not a ceiling on the technology: it is a reformulation challenge. Research into flavour compounds and BSFL meal processing methods (fermentation, enzymatic hydrolysis, peptide fractionation) is active. The commercial opportunity for full replacement is real but not yet delivered at scale as of 2026.

Pricing note: BSFL protein currently sits above fishmeal on a per-tonne basis at mid-range market prices. On a cost-per-tonne-of-digestible-protein basis in salmon diets, accounting for the APD differential, BSFL is approximately 12-18 percent more expensive than fishmeal at 2023 prices. This gap narrows when fishmeal prices spike above 1,900 EUR per tonne, which happened twice in the decade to 2024. It closes further at larger BSFL production volumes as facility capex is amortised over higher throughput.

The Practitioner View: Feed Compounder Operations

A feed compounder integrating BSFL protein meal into an aquaculture formulation works through four operational considerations specific to this protein source. These differ materially from the poultry feed case due to the higher nutritional demands of carnivorous fish species.

First, defatting specification. Commercial aquaculture BSFL meal is defatted: the larval oil is mechanically pressed or solvent-extracted before drying. The resulting meal contains 48-55 percent crude protein, less than 10 percent fat, and 8-15 percent chitin. The extracted oil is sold separately as BSFL oil, which has market value as a high-lauric-acid lipid for pet food and certain aquaculture species. The defatted meal specification allows more precise fatty acid control in the fish feed formulation.

Second, amino acid balancing for fish. Atlantic salmon have specific requirements for methionine, lysine, and in particular taurine, which is found in fishmeal but largely absent in BSFL meal. Taurine supplementation at 0.3-0.5 percent of the diet is required when fishmeal is substantially replaced with BSFL meal in salmon formulations. Lysine levels in BSFL are adequate; methionine requires supplementation at replacement rates above 25 percent.

Third, fatty acid replacement. The omega-3 deficit in BSFL meal (negligible EPA and DHA content) requires supplementation from fish oil or algal oil when fishmeal inclusion drops below levels sufficient to supply these fatty acids. Standard Norwegian salmon certification (GlobalG.A.P., ASC) sets minimum omega-3 content requirements for farmed salmon. At 25-50 percent fishmeal replacement with BSFL, maintaining these requirements is achievable with supplemental fish oil; the cost of the supplementation should be included in the BSFL substitution calculation.

Fourth, palatability and feed intake management. Salmon farms using automatic feeders with cameras or acoustic sensors to monitor feed wastage may see increased wastage in the first 1-2 weeks of transitioning to BSFL-inclusion diets, as fish adapt to the different flavour profile. Gradual transition protocols (increasing BSFL inclusion over 4-6 weeks rather than switching immediately) reduce this adaptation period and reduce the feed wastage penalty. Most commercial aquaculture operations using BSFL report normal feed intake within 2-3 weeks of the transition.

Where It Fits: BSFL in the Aquaculture Loop

BSFL is the most cost-effective fishmeal substitute in regenerative aquaculture at current commercial scale, specifically for freshwater and brackish species (tilapia, carp, catfish) and for salmonids at partial inclusion. The supply constraint argument is the primary driver; the direct cost comparison is secondary but improving with facility scale.

The full loop closes when aquaculture waste (sludge from recirculating aquaculture systems, pond sediment from pond systems) returns to the soil nutrient cycle through composting or direct application. This connects BSFL directly to both the composting pillar and the regenerative agriculture framework. BSFL frass and aquaculture sludge combined in a compost windrow produce a nitrogen-dense biofertiliser that is higher in available nitrogen than either input alone, and the chitin from the BSFL fraction activates plant immune priming throughout the compost pile.

For aquaculture operators running integrated systems, the BSFL sourcing decision connects to their own waste management cost. An integrated RAS (recirculating aquaculture system) co-located with a BSF bay and a hydroponic or soil-based growing operation creates a nutrient loop where protein waste from the fish becomes plant feed after passing through the BSFL bioconversion step, and where fish feed costs are partially offset by the tipping fee income from accepting food industry waste streams. This is the practical expression of the loop-closure lens that frames the entire Pillar 4 subject.

The broader picture: global aquaculture fishmeal demand is approximately 3 million tonnes per year and growing. Current global BSFL protein production is estimated at 50,000-80,000 tonnes per year, covering roughly 2-3 percent of aquaculture fishmeal demand. The ceiling is not biological or regulatory; it is capital deployment and facility construction. Every tonne of BSFL production capacity built replaces a tonne of fishmeal demand that the ocean fishery will not otherwise be able to supply at stable prices. The math closes as facility scale increases and the cost per tonne of BSFL production falls toward the structural floor enabled by negative-cost feedstocks.

For the operator running a modest BSFL bay (5-15 TPD) supplying a regional aquaculture cluster: the key commercial question is whether local tilapia or trout producers will pay the premium for a locally sourced, traceable protein meal versus imported fishmeal from Peru or Chile. In most European and Southeast Asian markets, the answer is yes for certified organic, BAP-certified, or ASC-certified aquaculture operations where supply chain transparency is a customer requirement. The premium is real. The conversion math and the biology establish whether you can deliver it.