A collaborative research team from the University of Idaho’s Aquaculture Research Institute and the USDA has identified key genetic markers that could transform feed strategies in rainbow trout aquaculture. Their findings, published in Aquaculture Reports and set for print in the journal’s April 15 edition, highlight a new opportunity for trout farmers to lower production costs and enhance sustainability without sacrificing fish quality.
The study, titled “Potential Physiological Mechanisms Behind Variation in Rainbow Trout (Oncorhynchus mykiss) to Biosynthesize EPA and DHA When Reared on Plant Oil Replacement Feeds,” zeroes in on trout strains that efficiently accumulate health-promoting omega-3 fatty acids (EPA and DHA) when raised on plant-based diets.
This development is particularly significant for Idaho’s Magic Valley—the nation’s leading rainbow trout production region—where producers have long relied on fishmeal and fish oil to deliver omega-3s. These marine-based ingredients are costly and environmentally burdensome. In contrast, plant-based feeds derived from crops like soy and canola offer a more sustainable and economical alternative but traditionally lack the ability to support omega-3 synthesis in trout.
Through more than five generations of selective breeding at the university’s Hagerman Fish Culture Experiment Station, researchers have developed trout that not only tolerate but thrive on plant-based diets—producing higher omega-3 levels than those fed traditional marine-based feeds.
“This gives producers the option to raise a different strain of trout that significantly reduces feed costs while delivering a high-quality, nutritionally superior product,” said Dr. Jacob Bledsoe, U of I assistant professor and Extension aquaculture specialist and co-author of the study.
The team pinpointed fatty acid binding proteins (FABPs) as a key genetic factor. These proteins transport lipids to the liver, where they are metabolized into omega-3s. Trout with elevated levels of FABPs showed a strong correlation with enhanced omega-3 deposition.
“We identified specific markers in the lipid pathway—particularly fatty acid binding protein—as central to this trait,” Bledsoe noted. “Our multi-generational research confirms we can reliably select for it.”
The research not only enhances the viability of plant-based aquaculture feeds but also offers a roadmap for applying similar genetic strategies to other fish species—helping drive the industry toward a more sustainable and efficient future.