Are Algae Supplements More Sustainable Than Fish Oil
By most environmental measures, algae cultivation outperforms fish oil extraction. But "more sustainable" is a comparative claim, not an absolute one. The comparison depends on which metrics you measure and how honestly you account for the inputs on both sides. We make algae supplements and we do not make fish oil, so our commercial interest is obvious.
Our motivation is to give you the honest comparison rather than a greenwashed summary, because the genuine environmental case is strong enough without embellishment.
How Fish Oil Production Affects Marine Ecosystems
We covered this in detail in our fish stock pressure article. Millions of tonnes of forage fish (anchovies, sardines, menhaden) are harvested annually for reduction into fish oil and fishmeal. These fish are keystone species in marine food webs, and removing them at industrial scale affects the seabirds, marine mammals, and larger fish that depend on them.
Bycatch is inherent to the fishing methods used, and diesel-powered trawlers carry their own carbon footprint.
Well-managed fisheries operate within catch limits, and certifications like the Marine Stewardship Council provide some assurance of responsible extraction. But "sustainable" in the context of wild fisheries means "extracted at a rate the population can tolerate," not "no ecological impact." The extraction still happens, and the ecosystem still absorbs the pressure.
How Algae Cultivation Compares on Sustainability
Algae grown in closed photobioreactors remove nothing from a marine ecosystem. No fish caught, no bycatch, no forage species depleted, no trawler fuel burned. The EPA and DHA are produced by cultivated organisms using filtered water, CO2, and light. We covered the carbon picture separately.
The trade-offs are real. Closed systems require electricity for lighting, pumping, and climate control, and unless powered by renewables that electricity has a carbon footprint. The infrastructure is more capital-intensive than a fishing boat, and production volumes are currently smaller, which keeps per-unit costs higher. We were honest about these inputs in our sustainability article and will not pretend they do not exist here either.
The Sustainability Comparison by Metric
- Wild population impact: Fish oil extracts from wild stocks, while algae cultivation extracts from nothing. Algae wins categorically on this measure.
- Bycatch: Fishing has inherent bycatch, and cultivation has none. Algae wins categorically.
- Marine habitat disruption: Trawling disrupts seabed habitats, while photobioreactors sit on land with no marine contact.
- Carbon footprint: Fishing fleets burn diesel, and algae cultivation uses electricity with CO2 as an input. Algae likely wins, but the margin depends on the energy source powering the facility.
- Water use: Algae systems use filtered water and can recycle it more efficiently than open-ocean fishing, which does not "use" water in the same sense.
- Land use: Fishing uses no land, while algae facilities require land for infrastructure. Fish oil wins on this narrow metric.
- Energy intensity per gram of omega-3: Uncertain, depending heavily on the specific facility, scale, and energy source. Published lifecycle assessments vary considerably.
What Your Individual Purchase Actually Achieves for Sustainability
Switching from fish oil to algae omega-3 removes your personal consumption from the extractive supply chain. It does not save a fishery on its own. The supplement market is a fraction of total fish oil demand, because aquaculture feed is the dominant use.
But removing your consumption from the extractive model is a legitimate choice even if the aggregate impact is modest. We made the same honest assessment in our fish stocks article: proportionality matters, and overstating your individual impact would be as dishonest as ignoring the systemic difference.
What our research found
Published LCAs show algae oil has 30 to 40 per cent lower climate impact than fish oil. The carbon advantage comes from fishing fleet fuel elimination and photosynthetic CO2 uptake. But the picture is not uniformly favourable. One assessment found heterotrophic algae oil (grown on sugar, not light) requires 5,000 times more water than fish oil due to feedstock cultivation.
The cultivation method determines whether the sustainability claim holds. Photosynthetic systems like photobioreactors use filtered water and CO2 as inputs with minimal agricultural footprint. Fermentation-based systems that rely on sugar feedstocks carry the water and land-use burden of agriculture. If sustainability matters to you, ask whether your algae product is photosynthetically grown or fermentation-derived. The answer changes the environmental arithmetic.
This distinction shaped how we position our two products. ULTANA Phytoplankton uses photosynthetically grown Nannochloropsis in sealed photobioreactors — filtered water, CO2, light. Clean Omega DHA uses fermentation-derived Schizochytrium. We do not make equivalent sustainability claims for both because the production routes are genuinely different. The fermentation route produces the DHA no photosynthetic species delivers at useful concentrations.
Sources
- Cottrell RS et al. A review of the global use of fishmeal and fish oil and the Fish In:Fish Out metric. Sci Adv. 2024;10(42):eadn5650. PubMed
- Naylor RL et al. Feeding aquaculture in an era of finite resources. Proc Natl Acad Sci USA. 2009;106(36):15103-15110. PubMed
- Gong Y et al. Comparative life cycle assessment of heterotrophic microalgae Schizochytrium and fish oil in sustainable aquaculture feeds. Elem Sci Anth. 2022;10(1):00098. DOI
Cara Hayes, MSc Nutrition and Dietetics (University of Sydney), writes all content in the Phytality Knowledge Centre. Read our editorial policy.
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult your GP or a qualified healthcare professional before starting any supplement.
Methodology and Disclosure
Phytality manufactures algae-based omega-3 supplements and does not sell fish oil. We have a direct commercial interest in the sustainability comparison favouring algae. Fishery data reflects FAO reports, and environmental comparisons reflect published lifecycle analyses. We have not completed a formal LCA of our own facility. Our comparison framing is editorial, not a certified environmental claim.
Last reviewed: March 2026
