Insect meals are being advocated as THE SOLUTION in far too many aquaculture development proposals and studies.
The science is abundant. Insect meals could have a role in replacing much of the fish meal in different segments of aquaculture production cycles for fed, lower trophic level aquatic animals such as tilapias and for juveniles stages of more carnivorous species. But, the economics of growing aquaculture species at a larger scale using insect meals are not viable.
Well-known problems for large scale insect meal production due to technical, expertise and other factors persist. According to Manna Insect of Finland (https://www.mannainsect.com/challenges-in-mass-producing-black-soldier-flies/), challenges in mass-producing black soldier flies at scale are: “(1) maintaining optimal environmental conditions, (2) ensuring consistent and nutritious feedstock, (3) managing reproduction and egg collection, (4) preventing disease and contamination, and (5) automating and scaling production”.
Insects are questionable solutions for replacement of fish meals in regions where large amounts of wastes such as spent brewery wastes are available.
Glencross et al. (2025) published an insightful study where they extracted proteins from spent brewery grains using well-known chemical engineering and compared their use in fish to feeding spent brewery grains to insects and then feeding cultured insects to fish as fish meal replacements.
The World drinks a LOT of beer (I contribute regularly), so there’s a lot of spent brewery grains out there ... from Glencross et al. (2025) “the volumes that exist are substantial, with global beer production estimated at just under 200 billion litres, and 200 g of spent brewery grains produced per litre of beer, resulting in 40 million tonnes of spent brewery grains produced annually (Statista, 2024)."
Glencross et al. (2025) state that…“there are massive differences between the potential yields from a brewery protein isolate…versus a black solider fly approach”...and that “This has important implications for potential feed protein security, as it shows that from a single tonne of spent brewery grains we can get more than a 1000 % difference in protein yields by promoting production of brewery protein isolate rather than black solider fly meal production. As such, we suggest that feed grade materials, such as spent brewery grains, should not be used in the production of black solider fly as it represents a substantial loss of protein from the fish feed-chain.”
“This has important implications for potential protein security, as it shows that from a single tonne of spent brewery grains we can get a 1235 % difference in protein yields by using an IP approach.”
“As such, we suggest that feed grade materials such as spent brewery grains should not be used in the feeding of black solider fly as it represents a substantial loss of protein from our feed chain, especially when there are better options for use of the spent brewery grains available.”
