Microalgae feed replaces fish ingredients without reducing trout growth in tests

UC Santa Cruz researchers replaced all fish-derived ingredients in rainbow trout feed with microalgae and canola oil without reducing growth or digestion in a study lasting more than two months. The work, published in Antioxidants, also found that the fish appeared to retain their nutritional quality for human consumption. The formulation combines two microalgae species, with taurine and lecithin helping trout accept the feed. Subsequent trials at Mt. Lassen Trout Farm and a California Department of Fish and Wildlife hatchery found no statistically significant growth difference against commercial feed. The researchers say larger-scale evaluation is still needed. Microalgae byproducts remain costly partly because their reuse from commercial production is not widely established.