Essential oils cut sea lice (Lepeophtheirus salmonis) by 68% in aquaculture

In brief:

• Consumer pressure, combined with governmental directives, is driving the aquaculture sector to reduce mortality, in line with wider animal protein production rates, to around 5%
• Making fish welfare the central focus of production is considered the best way to achieve a reduction in mortality rates. Using a toolbox approach, including products such as essential oils, can improve oxidative stress and disease resistance
• The recent study confirmed the impact of the product on sea lice (Lepeophtheirus salmonis) infestation/attachment in aquaculture species. In Atlantic salmon, Digestarom® PEP MGE achieved a 68% reduction in total lice compared to the control, demonstrating a clear and significant decrease in parasite load while maintaining strong zootechnical performance

Tackling aquaculture’s twin challenges: mortality and parasites

Under growing consumer scrutiny and tightening governmental directives, the aquaculture industry is under pressure to match mortality rates in other animal protein sectors. For high-value marine species like Atlantic salmon, parasites such as sea lice (Lepeophtheirus salmonis and Caligus rogercresseyi) are among the biggest threats to welfare and survival, increasing stress, being an entry point of secondary infections, and reducing feed intake.

The Norwegian government’s 5% mortality target by 2035 is driving innovation across management, genetics, vaccines, functional feeds, and predictive technologies such as AI. But parasite control remains critical, and chemical treatments face challenges from environmental concerns, resistance development, and welfare implications.

Digestarom® PEP MGE: essential oils with essential impact

Essential oils are complex mixtures of volatile compounds extracted from plants, are emerging as a powerful welfare management tool. Studies show the ability of essential oils to influence a broad range of physiological responses in fish, for example, when being handled, transported, or when exposed to disease. Digestarom® PEP MGE has a multi-functional mode of action and proven benefits in performance and health across multiple aqua species. The formulation, based on oregano, orange, and anise oil, is designed to support both gut and systemic health. It stimulates appetite and digestive secretions, enhances gut motility and microbiota modulation, provides anti-inflammatory and antioxidant effects, as well as improves mucosal protection.

In a controlled salmon trial, three dietary inclusion levels of Digestarom® PEP MGE were tested. Sea lice (Lepeophtheirus salmonis) challenge was introduced on day 52, and by day 105:

• The 800 g/t group showed a 68% reduction in total lice (Lepeophtheirus salmonis) compared to the control.
• Both the 800 g/t and 1,200 g/t groups had significantly fewer lice per fish.
• The percentage of fish with zero female lice (Lepeophtheirus salmonis)  increased significantly, indicating a preventative effect (Chart 3)
• Growth performance matched that of untreated fish, proving lice control without compromising productivity.

The outcome is a dual result: health protection and performance maintenance, in high-value species like Atlantic salmon.

A tool for the 5% mortality goal

Sea lice aren’t just a performance issue; they’re a mortality driver. By reducing lice (Lepeophtheirus salmonis) loads dramatically without chemicals, Digestarom® PEP MGE helps producers protect fish, maintain growth, and align with market and regulatory demands for sustainable, solutions.

Essential oils in aquaculture have already been shown to:

• Reduce oxidative stress markers and boost antioxidant enzymes
• Support immune function, mucosal defenses, and stress recovery

Now, with a proven 68% reduction in sea lice, their role as an “essential” part of the aquaculture toolbox is clearer than ever.

Looking Ahead

The path to five percent mortality will require multiple complementary solutions, but Digestarom® P.E.P. MGE’s combination of parasite control, gut health benefits and performance stability offers an immediate, scalable and welfare-friendly option for producers.

Crucially, this integrated approach is expected to reduce the number of sea lice (Lepeophtheirus salmonis and Caligus rogercresseyi) treatments required during the grow-out cycle, a tangible benefit for farmers in terms of lower handling stress, reduced chemical use and simpler farm management. With fewer lice, healthier fish and less reliance on treatments, the aquaculture sector moves one step closer to sustainable, high-welfare production and one giant leap away from sea lice (Lepeophtheirus salmonis and Caligus rogercresseyi) dominance.