Bridging the Feed Protein Gap in Aquaculture with Single Cell Protein

Because aquafeed accounts for up to 70% production costs and up to 80% of a producer’s environmental footprint, the opportunity for more sustainable aquaculture through greater efficiency encompasses costs savings, risk mitigation and an enhanced environmental profile. Recent aquafeed price increases of up to 30% reflect more than simply price increases of commodities such as fish meal, fish oil, wheat and soy. The severity of this raw material price impact on feed prices is also related to a limited raw material basket, and the fact that our drive to extend the raw material basket with novel, more sustainable proteins is only partly successful.

For example, the Norwegian salmon industry has diversified its use of marine ingredients by increased use of trimmings meal in the last decade. There has also been the use of guar protein as a new raw material in recent years. At the same time, there is still a large reliance on soy protein concentrate as a key raw material in salmon feeds in Norway, for example. The limited availability of sustainable proteins –referred to as the protein gap or protein crunch– highlights a potential limitation to the industry’s future sustainable growth. In the last years, many companies are also making a commitment towards decarbonization and have signed up to science-based targets to reduce greenhouse gas emissions by 2030 ( This list of companies also includes aquafeed and salmon farming companies, and the pressure is on as time is moving fast towards 2030 (Table 1). Feed ingredients with lower environmental footprints will be a critical part of the industry’s strategy to meet science-based climate targets.

Table 1. A selection of salmon and aquafeed companies’ commitments to Science Based Targets (Source:
CompanyBase YearTarget % reduction GHGTarget Year
Scope 1Scope 2Scope 3
Skretting / Nutreco Inc.20183030582030
Mowi ASA20163535-2030
Mowi ASA20167272-2050
Mowi ASA2018--352030
Mowi ASA2018--722050
Grieg Seafood ASA20183535352030
Salmar ASA20204242422030

Novel proteins

The aquaculture industry’s progress on sustainability relies heavily on diversifying its raw material basket for proteins but these new or novel raw materials must have a lower footprint. So it’s fair to say that the baseline criteria of novel protein ingredients to gain industry acceptance include concentrated protein levels, digestibility and an essential amino acid balance to meet aquaculture species’ needs, sufficient volumes, the right price and a lower environmental footprint.

Examples of novel ingredients recognised as potential candidates include algal oil, insect meal and single-cell protein. Algal oils, such as the EPA + DHA product Veramaris™, are the frontrunners when it comes to the commercial use of novel raw materials. While in 2021 less than 1% of raw materials in Norwegian salmon feeds were classified as novel, several large salmon feed companies in Norway made commitments in 2022 to the use of algal oil in the future. Although insect companies have caught attention recently and have been the darling of capital investment since EU regulations allowed their use in aquafeeds in 2017. However, single cell proteins have also been demonstrated to deliver performance in fish and have the greatest potential to improve the sustainability of aquafeeds and aquaculture production due to its potential to reach appropriate scale, meet expectations on market conditions and deliver a net zero greenhouse gas footprint.

The promise of single cell protein

Microbial or single cell proteins (SCP) are the frontrunner when it comes to emerging proteins. The category covers various types of micro-organisms and there are over 1 billion species spanning bacteria, fungi, yeast and algae and from this 1 billion there are a number of candidates with potential for industrial application. Single cell proteins or microbial proteins produced by fermentation technology have a massive potential for scalability. In addition, they are regarded as a protein production powerhouse; having very high growth rates these organisms can produce a considerable amount of protein compared to their initial weight. Other advantages include factors such as shorter generation times, the ability to use different feedstocks or substrates, no requirements for land and the possibility to produce continuously throughout the year in any part of the world. In addition, single cell proteins generally have a high protein content and contain all or most essential amino acids required by fish for growth and development. Flexibility in the use of different feedstocks is important, and examples include glucose, agricultural waste, and gases such as methane and carbon dioxide. Some examples of single cell proteins used for potential novel ingredients are given in Table 2.

Table 2. Overview of single cell feed proteins by species and organism type.
Type of organismProtein content rangeCharacteristicsExamples

Different feedstock choice possible

Production of vitamins and micro-nutrients

Saccharomyces cerevisiae

Candida utilis


High protein content

Growth on C1 substrates

Methylococcus capsulatus

Cupravidus nectar

Microalgae60-70%Phototropic growth & production of omega 3 fatty acids

Chlorella vulgaris

Desmodesmus sp.

Fungi30-50%Different feedstocks possibleMyrothecium verrucaria

Environmental picture

Single cell protein production has the potential to be net zero for the aquaculture industry in terms of carbon emissions and resource usage. This means that its production does not contribute to the increase of greenhouse gas emissions or consume a significant amount of non-renewable resources.

The sustainability of single cell proteins for use in aquafeeds are often attributed to zero land use, and with a picture of a large industrial fermentation unit this is easy to imagine. And in the future it will not just be about GHG emissions, there is also an increasing focus on biodiversity as an indicator of environmental impact and initiatives towards science-based targets for nature are already established. However, we also must consider the environmental impact of the feedstock used to feed the single cell proteins. The choice of feed stock, as with choice of raw materials in aquaculture feeds, also drives the footprint as well as the economics of the single cell protein.

Salmonid feeding trial results

Early prototypes of a single cell protein produced by researchers at the dsm-firmenich Bioscience Centre in Delft, The Netherlands showed excellent performance comparable to feeds containing fish meal and soy protein concentrate. Rainbow trout were grown for 12 weeks on different inclusions of SCP ranging from 0%, 5%, 10% to 20% on extruded feeds, with single cell protein replacing a combination of fish meal and soy protein concentrate. The data is shown in Figure 1, indicating that single cell protein inclusion has no negative impact on fish performance measured by final body weight.

Figure 1. The effect of single cell protein inclusion on the growth performance of rainbow trout. (Source: dsm-firmenich)

Proving environmental footprint reduction

To gain acceptance in today’s industry, novel raw materials will also have to have a low environmental footprint and especially with the focus on a shift to green energy – the potential to deliver at scale, with zero carbon intensity and with zero land use. Stakeholders along the value chain are expecting the industry to measure its environmental impact and reduce it. Accurate footprint measurement is essential and full life cycle assessment is becoming more important. But how to measure? dsm-firmenich has been working with leading animal protein producers to accelerate the use of life cycle assessment (LCA) in their operations. dsm-firmenich's intelligent sustainability service, Sustell™, is an ISO 14040/44 assured system that combines measurement with practical, science-based, proven solutions to unlock the value of sustainability across different animal species and farming systems. Today, full LCA footprinting is becoming more commonplace to assess and improve the sustainability of aquaculture operations.


Whilst aquaculture feeds have reduced their dependency on marine ingredients from fisheries and trimmings there is still a significant reliance on soy protein. Availability of novel raw materials rich in protein would bring with it stability of supply and economics as the aquaculture industry grows. If the production of novel protein raw materials at scale with market conditions was easy, we would have these technologies available today. It will take industry-wide commitment and capital investment, possibly co-investment by stakeholders to make this a reality. Collaborating across the value chain is key to drive the continued sustainable production of aquaculture, every member of the value chain has a role to make this happen and enable production at scale of single cell protein.

This article originally appeared in International Aquafeed.

Published on

16 June 2023


  • Aquaculture
  • Eubiotics
  • Veramaris®

About the Author

Louise Buttle - Key Accounts Aqua Global, Animal Nutrition & Health at dsm-firmenich

Louise holds a PhD obtained at the University of Hull, UK. She has over two decades of industry experience in aquaculture, much of this time with EWOS and Cargill in the salmon farming countries; Scotland, Chile, and Norway. Louise held various positions in R&D, product development, innovation, and sustainability. She joined dsm-firmenich in May 2019 and is committed to delivering solutions supporting the further development of sustainable aquaculture.


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