A study published in Fish & Shellfish Immunology, conducted under real commercial farming conditions, confirmed that Futerpenol® reduced Atlantic salmon mortality by 61% during a harmful algal bloom (HAB) event, with immune activation still measurable weeks after supplementation had ended.
Functional feeding is shifting from an occasional supplement to a core part of baseline nutrition in salmon farming. That's the finding of a study led by researchers from Chilean and Norwegian institutions, working alongside a national salmon producer, which evaluated under real production conditions how different functional diets shape innate and adaptive immunity in Atlantic salmon, and what happened when those fish faced an unplanned real-world environmental event.
Key concept
What is an immunomodulator in salmon farming?
It's a functional additive that strengthens the fish's innate and adaptive immune response specifically when it faces a sanitary or environmental challenge, unlike an immunostimulant, which keeps the inflammatory response permanently switched on. This mechanism supports allostasis: the balance between the fish's immune system and its environment throughout the production cycle.
A Commercial-Scale Trial, Not a Lab Study
The study took place at a Salmones Camanchaca farming site in Contao, Región de Los Lagos, with 75,000 post-smolt per cage, under the same conditions the industry typically works with. Over 90 days, fish received one of three diets: the commercial New Power® diet from BioMar Chile (control), that same diet supplemented with Pack Salud (beta-glucans, nucleotides and vitamin C), or the diet supplemented with Futerpenol®, Aqua Health by MNL Group's additive based on algae fucoidans and labdane diterpenes. After the 90 days, all groups returned to the conventional diet for six additional weeks.
Samples were taken at four points: t0 (baseline), t1 (day 34), t2 (day 90) and t3 (42 days after withdrawing the functional diet), analyzing immunity-related gene expression in head kidney, gills and spleen. Unexpectedly, between t2 and t3 the site experienced a natural harmful algal bloom (HAB), which made it possible to observe how fish already primed by the functional diets responded to a real environmental event rather than a simulated one.
The Result: 61% Lower Mortality During the Algal Bloom
Production performance showed no differences between groups. Growth, weight gain and length were unaffected by diet, confirming that the goal of these additives isn't to accelerate growth, but to modulate the fish's physiology.
The difference appeared once the algal bloom hit. While the Pack Salud group showed 10% lower mortality than the control, salmon fed Futerpenol® showed a 61% reduction in mortality against that same control, the strongest protective effect observed among the treatments evaluated.
What's Behind It: An Immune Response That Persists Over Time
By day 34, both functional diets already showed higher expression of innate and adaptive immunity biomarkers, suggesting the immune system was activating before any visible sanitary challenge. Fish fed Futerpenol® showed more pronounced modulation of pro- and anti-inflammatory cytokines (IFNg, IL-10, IL-12, TNFa) and cellular markers such as CD4, CD8, CD83, CD86, MHC I and MHC II in head kidney and spleen, indicating immune cell activation, along with higher expression of antimicrobial peptides (cath2, hepcidin) and immunoglobulins (IgM, IgT).
What stands out most: this activation wasn't limited to the supplementation period. At the final sampling point, taken 42 days after withdrawing the functional diet, the Futerpenol® group still showed higher immune activation than fish on the purely commercial diet, evidence of sustained immunomodulation over time, particularly in the head kidney, the salmon's main hematopoietic and immune organ.
Immunomodulator, Not Immunostimulant: The Difference Behind the Result
According to Hugo Martínez, Customer Satisfaction Manager at Aqua Health by MNL Group, the key lies in how Futerpenol® works. Unlike an immunostimulant, which keeps the inflammatory response permanently active at a higher energy cost, Futerpenol® strengthens innate and adaptive responses only when the fish faces a real sanitary or environmental challenge. Once the stress factor is gone, energy goes back toward growth, supporting allostasis, the balance of the immune system with its environment throughout the grow-out cycle.
"The immunomodulator boosts immune system activation only when the fish actually needs it. Once the stress factor is gone, the response returns to normal and energy goes back toward growth."
Hugo Martínez, Customer Satisfaction Manager, Aqua Health by MNL GroupMartínez also referenced a 2023 Aquabench study that recorded a nearly 3% increase in specific growth rate (SGR) among fish fed Futerpenol®, attributable to better use of available energy when stress factors are absent.
Results From Farms Using It Continuously
Beyond the study itself, results observed during 2026 at sites with sustained use of Futerpenol®, now often combined with Maqui XT®, MNL Group's antioxidant maqui extract aimed at tissue repair, show reductions of close to 50% in melanosis, better fillet color, lower visceral fat and higher carcass yield. Sites also report at least a 50% reduction in antibiotic use compared to sites not using Futerpenol®, with a return on investment close to 15 times.
When to Start Supplementing
Zones historically affected by algal blooms are already well identified, with the highest risk concentrated between November and March. Aqua Health by MNL Group recommends starting supplementation in August or September, so fish enter the highest-risk period in stronger physiological condition and carry that immune support through the full season.
With harmful algal blooms expected to become more frequent as a result of climate change, this evidence reinforces the role of functional nutrition as part of sanitary planning, not a reactive response, but physiological preparation ahead of time.
Study cited
"Modulation of innate and adaptive immunity in Atlantic salmon (Salmo salar) fed diets containing commercial-like additives under farming conditions in seawater phase." Fish & Shellfish Immunology, Elsevier.
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Aqua Health by MNL Group's immunomodulator for more resilient salmon farming.
Frequently Asked Questions
How much did Futerpenol® reduce mortality during the study's HAB event?
By 61% versus the control group, according to the study published in Fish & Shellfish Immunology, conducted under real commercial farming conditions at a site in Región de Los Lagos, Chile.
What is Futerpenol® and what is it made of?
Futerpenol® is a functional additive for aquaculture developed by Aqua Health by MNL Group, based on algae fucoidans and labdane diterpenes, with immunomodulatory properties.
What's the difference between an immunomodulator and an immunostimulant?
An immunostimulant keeps the inflammatory response permanently active, at a higher energy cost. An immunomodulator like Futerpenol® strengthens innate and adaptive immune responses only when the fish faces a real challenge, allowing energy to go toward growth the rest of the time.
When should Futerpenol® supplementation start ahead of HAB season?
Supplementation is recommended starting in August or September, since the highest risk of harmful algal blooms in Chile falls between November and March.
Do Futerpenol®'s effects last after supplementation stops?
Yes. The study observed higher immune activation in Futerpenol®-fed fish even 42 days after the functional diet was withdrawn, pointing to a sustained immunomodulation effect over time.