Study points to phospholipid sweet spot for salmon fry diets: full analysis

Version 2

A newly published Animals study suggests that getting phospholipid levels right in starter feeds could improve early performance in Atlantic salmon fry, regardless of whether those phospholipids come from soybean lecithin or krill oil. In a 56-day feeding trial, researchers found that added phospholipids improved growth, antioxidant capacity, and lipid metabolism, while reducing whole-body lipid deposition. Notably, the paper reports no significant growth-performance difference between soybean lecithin and krill oil phospholipids when they were compared at equivalent inclusion levels. (mdpi.com)

That finding lands in a well-established area of salmon nutrition research. Earlier studies have shown that Atlantic salmon fry have a higher phospholipid requirement in early life than older fish, in part because young fish appear to have limited capacity for de novo phospholipid synthesis and lipoprotein-mediated lipid transport. Previous salmon work comparing krill oil and soybean lecithin also found that supplemental phospholipids can improve growth and survival in fry, although the relative advantage of marine versus plant phospholipids has varied by trial design, dose, and life stage. (sciencedirect.com)

In the new paper, the basal diet contained 1.76% phospholipids, and the investigators added 1.5%, 3.0%, or 4.5% phospholipids from either soybean lecithin or krill oil phospholipids. According to the journal summary, 3.0% to 4.5% soybean lecithin and 1.5% to 4.5% krill oil phospholipids significantly improved growth performance, while feed conversion ratio fell significantly in the 3.0% to 4.5% soybean lecithin groups and in the 3.0% krill oil group. Phospholipid supplementation also reduced whole-body lipid deposition, increased visceral lipase activity in all but the lowest soybean lecithin group, and improved antioxidant capacity across all supplemented groups. (mdpi.com)

The broader literature helps explain why that matters. Reviews and mechanistic studies describe phospholipids as central to membrane structure and lipoprotein formation, both of which are important for absorbing and transporting dietary fat during early development. A recent review on soybean lecithin in aquafeed notes that lecithin is widely used to meet phospholipid needs in larval and juvenile fish, and specifically cites Atlantic salmon research showing soybean lecithin was not significantly different from marine phospholipid sources for promoting fry growth in some experiments. At the same time, other Atlantic salmon studies have suggested marine phospholipid sources can show performance or tissue-health advantages under certain conditions, including freshwater pre-transfer phases. (frontiersin.org)

There does not appear to be substantial outside commentary yet on this specific paper, which was listed by Animals in its May 1, 2026 issue. Still, the industry context is familiar: aquafeed formulators are under pressure to balance fish performance, raw material costs, and sustainability goals. Soybean lecithin offers a more plant-based option, while krill-derived phospholipids bring marine lipid fractions rich in phosphatidylcholine and long-chain omega-3 fatty acids such as EPA and DHA. The study’s finding that similar growth outcomes were achieved at equivalent inclusion levels may therefore be commercially relevant, even if ingredient selection still depends on price, availability, and broader formulation targets. This is partly an inference from the nutrition and ingredient literature, rather than a direct claim made by the study authors. (mdpi.com)

Why it matters: For veterinarians working in aquaculture and fish health, feed composition is inseparable from welfare, robustness, and downstream disease resilience. Better early growth and improved lipid handling can affect uniformity, readiness for transfer, and possibly resilience under stress, while lower lipid deposition may be relevant to liver and metabolic health. Although this paper is a nutrition study rather than a disease challenge trial, it reinforces the idea that early-life diet formulation is a health-management tool, not just a production lever. It also gives veterinary teams a more nuanced talking point with nutritionists and producers: soybean lecithin may be a viable alternative to krill phospholipids in fry feeds when the goal is growth performance, but source-specific effects may still matter depending on stage, stress exposure, and the endpoints being prioritized. (mdpi.com)

What to watch: The next step is validation beyond controlled feeding trials, especially in commercial systems and across later freshwater and seawater phases. Future work worth watching includes cost-benefit comparisons, effects on transfer readiness and gill or gut health, and whether source-specific phospholipid effects become more important under stress, pathogen exposure, or lower-fishmeal formulations. (mdpi.com)