Fish oil vs. krill oil vs. algae oil vs. cod liver oil vs. calanus oil: what are the differences?

Omega-3 supplements come in many forms: from fish oil and krill oil to cod liver oil and plant-based alternatives such as algae oil. Although they all contain omega-3 fatty acids, they differ significantly in composition, dosage, form, and application.

In this guide, we compare the main omega-3 sources so you can better determine which is most suitable for you.

What should you look for when choosing an omega-3?

Most omega-3 supplements focus on two fatty acids: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Each source provides these fatty acids differently and within a different context.

Some oils offer a highly concentrated dose of EPA and DHA. Others provide a broader spectrum of fatty acids and bioactive compounds.

Omega-3 supplements also differ in several key aspects:

• Form (triglycerides, phospholipids, wax esters)
• Stability (sensitivity to oxidation)
• Source (fish, krill, plankton, algae)
• Degree of processing and heating

Together, these factors determine how an oil behaves in the body.

What are the main differences between omega-3 sources?

Characteristic	Calanus oil	Fish oil	Krill oil	Cod liver oil	Algae oil
Type of profile	Broad spectrum (40+ fatty acids)	EPA/DHA focus	EPA/DHA + phospholipids	Broad + vitamins	EPA/DHA focus
EPA/DHA dosage	Low–moderate	High (concentrated)	Moderate	Low–moderate	High possible
Form	Wax esters	Triglycerides / ethyl esters	Phospholipids + triglycerides	Triglycerides	Triglycerides
Source	Zooplankton	Fish	Krill	Cod liver	Microalgae
Oxidation sensitivity	Very low (natural antioxidants)	High/variable	Relatively low	Variable	Variable
Extra components	Astaxanthin, policosanols, SDA	–	Astaxanthin	Vitamin A & D	–
Processing	Minimal	Often highly processed	Moderately processed	Minimal	Controlled production
Sustainability	High	Variable	Under pressure	Reasonable	High

What types of omega-3 supplements are there?

What makes calanus oil different from other omega-3s?

Calanus oil is derived from Calanus finmarchicus, a zooplankton found in the North Sea, Norwegian Sea, and the northern Atlantic Ocean. Calanus sits at the bottom of the food chain, feeding on phytoplankton and deriving energy from photosynthesis. Due to its short lifespan of one year, it contains minimal environmental contaminants. This makes it a clean and sustainable source.

Calanus oil contains a full spectrum of 40 different fatty acids, including: ±15% monounsaturated, ±24% polyunsaturated, and ±16% saturated. However, its EPA and DHA content is lower than that of fish, krill, or algae oil.

Processing

The zooplankton is frozen directly on the boat to ensure freshness. During processing, nothing is added or removed from the zooplankton. No chemicals are used in oil production. The only input besides energy and fresh water is a minimal addition of enzymes. This process is carried out without solvents or additives and ensures gentle extraction of both lipids and proteins (hydrolysate). No further refining, concentration, or processing takes place.

Because it is minimally processed and complex, calanus oil—along with cod liver oil—comes closest to eating fresh fish.

Wax esters

What makes calanus oil unique is that its fatty acids are stored as wax esters. In this form, a fatty acid is bound to a fatty alcohol (policosanol). This makes the product less sensitive to oxidation than triglycerides and phospholipids. It also allows for gradual absorption in the body.

Additional bioactive compounds

• SDA (stearidonic acid) – an intermediate in the conversion to EPA
• Policosanols – known from plant sources
• Astaxanthin – a powerful antioxidant

With about 1.8 mg of astaxanthin per serving, this is significantly higher than many krill oil products (often around 0.1 mg).

In short:
Calanus oil is a minimally processed and stable source of omega-3, rich in additional nutrients. The EPA/DHA dosage is lower. Therefore, it is chosen as a nutrition-based foundation rather than a high-dose supplement. Ultimate Omega Formula from NoordCode is an example of a calanus oil supplement.

Is fish oil still the best choice?

Fish oil is often considered the omega-3 standard. It provides high doses of EPA and DHA.

Processing

Fish oil is essentially a concentrated omega-3 extract. It is the result of a long industrial process. Most fish oil starts in triglyceride form but is often converted into ethyl esters during production and sometimes back into triglycerides. These processes allow for high concentrations but affect absorption, stability, and oxidation.

Oxidation and quality

Fish oil is relatively sensitive to oxidation, partly due to heating during production and long storage periods. Therefore, quality strongly depends on freshness, added antioxidants, and origin. Fish oil from small fish such as sardines and anchovies is often cleaner and less contaminated. Oxidation values (TOTOX score) provide insight into product purity.

Sustainability

Sustainability plays a major role in fish oil. Producers extract the oil from wild fish, often small species like sardines and anchovies. These fish reproduce quickly, but intensive fishing disrupts ecosystems and food chains. Certifications such as MSC (Marine Stewardship Council) and Friends of the Sea help in making more sustainable choices, but the impact still depends on fishing practices, origin, and scale.

In short:
Fish oil is a high-dose source of EPA and DHA but undergoes intensive processing and is sensitive to oxidation. Quality therefore strongly depends on production, freshness, and origin. Sustainability remains an important consideration.

Is krill oil better than fish oil?

Krill oil comes from small crustaceans. It stands out due to the phospholipid form of omega-3 fatty acids. Krill oil also contains a small percentage of triglycerides. Its improved absorption is mainly attributed to the phospholipid structure.

Like calanus oil, krill oil naturally contains astaxanthin, which protects against oxidation. However, the amount is significantly lower than in calanus oil.

Processing

Krill oil falls between fish oil and calanus oil or cod liver oil in terms of processing. Producers process krill immediately after harvesting to prevent spoilage. Mechanical techniques or solvents are used to extract the oil. Krill oil remains closer to nature than much fish oil. Heavy concentration and conversion to ethyl esters are not required. However, it is not completely unprocessed. Extraction and refining are controlled to preserve phospholipids and astaxanthin.

Ecological impact

Krill oil may seem sustainable, but this is not entirely accurate. Krill forms the foundation of the Antarctic ecosystem, feeding whales and penguins. Fishing is strictly regulated but occurs in limited areas, putting pressure on the ecosystem. Climate change increases this pressure. Certifications such as MSC help but do not provide full assurance. If sustainability is a priority, algae oil or calanus oil is a smarter alternative.

In short:
Krill oil offers good absorption and antioxidants. It is somewhat more processed than calanus oil and raises questions about sustainability.

What is the difference between cod liver oil and fish oil?

Cod liver oil is a classic source of omega-3. Producers extract it from cod liver. It contains not only omega-3 fatty acids but also vitamins A and D. This makes it more of a complete nutritional product than an isolated supplement.

Processing

The fatty acids in cod liver oil naturally occur in triglyceride form, the same form as fats in your diet. Your body easily recognizes and absorbs this structure. No chemical processing is required, preserving its natural composition.

Extra virgin cod liver oil is considered the purest form, a minimally processed product comparable to calanus oil.

Its omega-3 content is lower than fish oil concentrates, but it offers a richer and more complete nutritional profile.

Oxidation

To limit oxidation, antioxidants such as rosemary extract or tocopherols are often added. The TOTOX score indicates the product’s purity.

Ecological impact

The sustainability of cod liver oil depends largely on its origin. It is often produced as a byproduct of fish caught for consumption, such as cod, which improves resource efficiency. However, it still depends on fishing. Pay close attention to origin and certifications.

In short:
Cod liver oil is a pure source of omega-3 in triglyceride form, with vitamins A and D. It provides less omega-3 than fish oil concentrates but offers a broader nutritional profile. Sustainability depends on origin and is often linked to fisheries byproducts.

Is algae oil a good alternative to fish oil?

Algae oil is the only plant-based source of omega-3 fatty acids. It is produced from microalgae in a controlled environment, offering several advantages. Because production is completely independent of the ocean, algae oil is a very clean source of omega-3. It is free from contaminants and does not burden ecosystems. It is also a logical choice for vegetarians and vegans.

Fatty acid profile

Algae oil contains pure EPA and DHA. It is therefore less complex than other omega-3 sources. Most algae oil products contain relatively more DHA and less EPA, making the composition less balanced.

Oxidation

Like fish oil and cod liver oil, algae oil is sensitive to oxidation. Adding antioxidants is important to maintain quality and stability. The TOTOX score indicates purity.

Processing

Algae oil is produced through controlled fermentation of microalgae. Naturally, fatty acids occur in triglyceride form. However, after extraction, the oil is often further processed to achieve higher EPA and DHA concentrations. This is frequently done through chemical concentration and re-esterification, where fatty acids are first separated and then reassembled. While this allows higher dosages, it also alters the original oil structure.

Differences in algae oil quality

Not all algae oils are the same. The microalgae (Schizochytrium sp.) used for NoordCode High EPA & DHA are naturally rich in EPA, making intensive processing unnecessary. The oil remains closer to its original state: without chemical concentration, without re-esterification, and with preservation of its natural fatty acid structure. This makes it possible to offer algae oil with relatively high EPA content without altering the oil structure.

In short:
Looking for a clean, plant-based omega-3? Algae oil is a strong choice. It directly provides EPA and DHA, often with more DHA. Many producers process algae oil to increase concentration, altering its original structure. This is not always necessary. Some variants remain pure and unprocessed and naturally contain more EPA, such as NoordCode High EPA & DHA.

Which omega-3 best fits your goal?

“The best” omega-3 does not exist. Choose one that fits your goal.

• Choose a broad-spectrum source (such as calanus oil or cod liver oil) if you:
  • want a nutrition-based approach
  • value natural complexity
  • prefer minimal processing
• Choose a concentrated EPA/DHA source (such as fish oil, krill oil, or algae oil) if you:
  • want a higher intake
  • want targeted EPA and DHA supplementation
  • want control over dosage
• Choose algae oil if you:
  • want a vegan omega-3
  • are looking for a clean and sustainable source
• Choose calanus oil if you:
  • place extra value on antioxidants such as astaxanthin
  • want a stable product less sensitive to oxidation
  • want a broader fatty acid profile

Which omega-3 is the best?

Omega-3 supplements differ fundamentally in composition and application. Some focus on high dosages, while others provide a broader and more natural fatty acid profile.

The best choice depends on what you are looking for: a daily foundation or targeted supplementation. Once you understand the differences, it becomes easier to choose what suits you best.