As demand for aquaculture feed rises alongside global seafood consumption, researchers at UC Santa Cruz have made a promising breakthrough: a sustainable, fishmeal-free feed that maintains fish growth performance using marine microalgae byproducts.
In a recent two-month study, scientists replaced fishmeal with leftover marine microalgae from the human supplement industry and found no decline in growth rates across all replacement levels—33%, 66%, and 100%. The feed was tested on rainbow trout, a species traditionally reliant on fish-based diets.
The success builds on earlier work developing microalgae-based diets for Nile tilapia, a more herbivorous species, and represents a step forward in solving one of aquaculture’s long-standing challenges: reducing reliance on wild-caught forage fish without compromising nutritional value or growth. Key to this latest breakthrough was the addition of taurine and lecithin, compounds that mimic the taste and nutritional cues of fishmeal.
While marine microalgae offer high levels of omega-3 fatty acids (DHA and EPA), production costs remain a major barrier to scaling. Lead researcher and assistant professor Pallab Sarker emphasized the need for industry investment: “This research shows the potential of microalgae, but affordability is still a hurdle.”
If commercial production costs can be reduced, microalgae could offer a scalable, ecologically responsible alternative to fishmeal—easing pressure on marine ecosystems while supporting continued growth in aquaculture.
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