Calanus oil:
why this is not just fish oil and what the difference means for your dog or cat
Joints that crack. Chronic low-grade inflammation that occurs everywhere at the same time. A skin or coat that never really becomes beautiful. Omega-3 supplements have been recommended for years, but most fish oil never reaches the place where it is supposed to work. Calanus oil works differently. Here’s why.
By Stefan Veenstra DVM
What is calanus oil and why is it different?
Calanus finmarchicus is a small crustacean, a copepod, that occurs in enormous numbers in the North Atlantic Ocean. It forms the basis of the arctic marine food web and is the food source for herring, jacks, whales and seabirds. The oil extracted from this organism is the only commercially available marine oil in which more than 80% of the fatty acids are bound as wax esters.
In regular fish oil, omega-3 fatty acids are bound as triglycerides. In krill oil as phospholipids. In calanus oil as wax esters: fatty acids esterified with long-chain fatty acid alcohols. This binding form determines how quickly the oil is digested, where in the intestine the fatty acids are released and which receptors they activate. And that makes a substantial difference.
What does calanus oil help with?
Calanus oil is widely applicable in dogs and cats, and in humans. The three most common applications in practice:
Osteoarthritis, hip dysplasia, stiffness and joint pain. Omega-3 fatty acids inhibit prostaglandin and leukotriene synthesis that drives joint inflammation. Calanus oil reaches the joint tissue more effectively than standard fish oil.
Dry skin, eczema, dull fur and excessive scratching. Omega-3 fatty acids improve the skin’s barrier function and lower the inflammatory threshold that drives itching responses.
Low-grade inflammation that puts stress on multiple organ systems. Calanus oil, via GPR120 receptor activation, modulates the NF-kB signaling pathway that drives most chronic inflammatory processes.
Calanus Oil vs Fish Oil: What Makes the Difference?
| Calanus oil | Fish oil | Krill oil | Algae oil | |
|---|---|---|---|---|
| Binding form | Wax esters (80%+) | Triglycerides | Phospholipids | Triglycerides |
| Release in gut | Slow, distal | Fast, proximal | Ground of appeal | Fast, proximal |
| GPR120 activation | ✅ Optimal | Limited | Moderate | Moderate |
| EPA content | Present | High | Present | Low to absent |
| DHA content | Present | High | Present | ✅ High (primary source) |
| Astaxanthin | ✅ Yes (red color) | No | Little | No |
| SDA for cats | ✅ High content | Low | Low | Not present |
| Suitable for vegans | No | No | No | ✅ Yes |
| Sustainability | ✅ <0.01% of biomass harvested | Variable | Good | ✅ Excellent (grown) |
A brief explanation of algae oil: algae are the original producer of omega-3 in the food chain. Fish become rich in EPA and DHA because they eat algae. Algae oil goes to the source. It is the only fully plant-based and sustainable omega-3 source with a significant DHA content, which makes it interesting for vegan-feeding people and as an alternative in animals with fish sensitivity. However, the EPA content in algae oil is low to absent in most commercial products, and the wax-ester bond form that makes calanus oil unique is completely lacking. Algae oil is therefore strong for brain support via DHA, but less suitable as a broad anti-inflammatory supplement than calanus oil.
The science behind the operation
GPR120: the receptor that fish oil does not reach properly
GPR120, also called FFA4, is a receptor on macrophages, intestinal cells, fat cells, and pancreatic cells. Activation of this receptor by omega-3 fatty acids inhibits the NF-kB and JNK signaling pathways that drive the production of pro-inflammatory cytokines such as TNF-alpha, IL-6, and IL-1beta. This is the central mechanism behind the anti-inflammatory action of omega-3.
GPR120 is most strongly expressed in the distal part of the intestine. Wax esters are broken down more slowly than triglycerides and release omega-3 fatty acids further back. They are basically natural slow-release molecules that deliver the fatty acids where the receptor response is strongest. Regular fish oil releases most of the omega-3 proximally, well before it reaches those receptors.
Animal study · Journal of Nutrition 2014 · Wax esters vs EPA/DHA ethyl esters
Höper et al. showed that wax esters from calanus oil improved metabolic effects more significantly in mice with diet-induced obesity than an equivalent dose of EPA and DHA in ethyl ester form. Calanus oil reduced fat cell mass, insulin resistance, and cardiovascular inflammation at significantly lower EPA and DHA doses per gram of product.
SDA: the omega-3 that cats can use
Cats lack the enzyme delta-6-desaturase and cannot convert ALA from vegetable oils to EPA. Stearidonic acid (SDA) in calanus oil skips that step and provides an omega-3 that cats can use immediately. Plant-based omega-3 supplements therefore offer hardly any therapeutic effect on cats. Calanus oil is.
Astaxanthin: red color, strong antioxidant
The red color of calanus oil comes from astaxanthin, one of the strongest antioxidants found in nature. Astaxanthin protects the polyunsaturated fatty acids in the oil from oxidation. Calanus oil is therefore more stable than regular fish oil, which quickly goes rancid. Astaxanthin also has its own anti-inflammatory and neuroprotective properties.
Review · Frontiers in Pharmacology 2020 · Wax esters and health effects
Schots et al. described the unique properties of wax ester oil: anti-inflammatory effects via GPR120 beyond EPA and DHA alone, anti-atherogenic effects via reduced cholesterol oxidation, and anti-obesogenic effects via GPR120-mediated insulin sensitization. A combination that no other marine oil supplement provides.
The European Commission accepted higher daily intake limits for calanus oil in December 2024: from 2.3 to 3.1 grams per day. This confirms the safety status as a Novel Food and gives room for stronger formulas. A further confirmation of the scientific status of calanus oil.
When do I use calanus oil?
Joint complaints dog
In addition to Mobility Support and PEA Complex. Calanus oil provides the systemic omega-3 base for anti-inflammatory while the other supplements support local cartilage structure.
Skin complaints dog and cat
As part of the Skin Protocol. Omega-3 fatty acids are essential for skin barrier function and lower Th2 dominance that drives atopic skin reactions.
Chronically ill cats
CKD, IBD, chronic inflammation. Cats benefit extra because of the SDA content. Plant-based omega-3 supplements hardly work in cats. Calanus oil is.
Basic daily support
For animals on kibble or one-sided feed where omega-3 deficiency is structural. Long-term basis for cardiovascular, cognitive and inflammatory health.
Old age and inflammaging
Older dogs and cats that are deteriorating on several fronts at the same time. Inflammaging, the chronic low-grade inflammation that drives aging, is directly inhibited via GPR120 activation. DHA in calanus oil also supports cognitive function and neuroplasticity in aging animals. Combine with Longevity Support for maximum synergy.
Quality: oxidation, packaging and farmed salmon
Oxidation: the hidden quality dropper
Polyunsaturated fatty acids are chemically unstable. Contact with oxygen, heat and light starts an oxidation chain that makes the oil rancid and forms harmful by-products: lipid peroxides, free radicals and aldehydes. Oxidized fish oil not only no longer works as an anti-inflammatory agent. It can actively have pro-inflammatory effects, the exact opposite of what you want to achieve.
The oxidation status of an oil is measured via three values: the peroxide value (PV), the anisidine value (AV) and the total oxidation value (TOTOX). The international standard of the GOED (Global Organization for EPA and DHA Omega-3s) sets a maximum PV of 5 meq/kg. Independent studies show that many products far exceed that standard. A study from New Zealand found that 83% of omega-3 supplements examined exceeded recommended peroxide limits. A large US study of 72 omega-3 supplements from 2024 found average PV levels of 6.4 versus the allowable limit of 5, with TOTOX levels on average close to the allowable limit.
Study · Journal of Dietary Supplements 2024 · 72 omega-3 supplements tested
Hands et al. analyzed 72 marine and microalgal omega-3 supplements for oxidation values over several years. They found significant heterogeneity in freshness, with a substantial proportion of the products showing increased oxidation markers. The study confirms that oxidation of omega-3 supplements is a real quality problem in the consumer market, regardless of the type of oil.
Packaging: pump bottle vs capsule
Liquid omega-3 oils in a pump bottle or open bottle are continuously exposed to oxygen after opening. Each pump introduces air into the bottle. At room temperature, this significantly accelerates the oxidation chain. A bottle that is left in the cupboard for weeks after opening, even if it still smells reasonable, can already contain significantly oxidized oil without this being visible or measurable to the consumer.
Capsules offer a structural advantage in this regard. The oil is sealed off from oxygen, light and moisture. High-quality capsules are also filled under a nitrogen atmosphere, so that the oil is hardly exposed to oxygen from production to ingestion. For polyunsaturated fatty acids, which are the most sensitive to oxidation of all nutrients, the capsule is therefore the safest form of packaging. A liquid oil can start out qualitatively, but deteriorate quickly after opening. One capsule retains its quality until the moment of ingestion.
Salmon oil and farmed salmon: omega-3 content and contaminants
Salmon oil is one of the most commonly used omega-3 sources for dogs and cats. The question of whether that choice is always wise deserves an honest answer.
Farmed salmon are now fed a diet that contains more and more plant-based ingredients and fewer and fewer marine raw materials. A Norwegian longitudinal study (ScienceDirect, 2025) that analyzed data from 2006 to 2021 showed a clear trend: the concentrations of EPA, DHA and DPA in farmed salmon decreased significantly during that period, while alpha-linolenic acid, linoleic acid and oleic acid increased. Farmed salmon has therefore acquired a different fatty acid profile in twenty years. Less omega-3, more omega-6. This has direct consequences for the therapeutic value of salmon oil as a supplement.
The contaminant issue is nuanced. Early studies, including a large-scale analysis of 459 farmed salmon versus 135 wild Pacific salmon (Hites et al., Environmental Science and Technology), found significantly higher levels of PCBs, dioxins, toxaphene, and dieldrin in farmed salmon than in wild salmon. More recent Norwegian studies show that contaminant levels in farmed salmon have decreased in recent decades due to stricter feed regulation and reduced use of fish oil and fishmeal in the feed. Current levels are well below the EU maximum limits. The consensus among regulators is that farmed salmon is safe food.
But for use as a therapeutic supplement in chronically ill animals, a lower threshold is more relevant. A lower omega-3 content due to feed modifications, combined with the oxidation sensitivity of salmon oil in liquid packaging, makes salmon oil as a supplement less predictable in therapeutic value than a controlled, certified omega-3 source such as calanus oil in capsule. The quality of salmon oil depends very much on the origin of the fish, the processing and the packaging. Without TOTOX certification from the supplier, you won’t know what you’re buying.
- Capsule over pump bottle or open bottle
- Peroxide value (PV) below 5 meq/kg, TOTOX below 26
- Nitrogen packing or antioxidant addition listed
- Origin and processing of the raw material transparent
- Third-party quality certification (IFOS, GOOD or equivalent)
Sustainability
Calanus finmarchicus is the most abundant crustacee in the North Atlantic Ocean. The total annual harvest is less than 0.01% of the annual growth, in accordance with Norwegian fisheries regulations. Harvesting is done with soft landing nets without bycatch. Calanus oil therefore has one of the lowest ecological footprints of all marine omega-3 sources.
Conclusion
Calanus oil is not an ordinary fish oil. Its wax ester bond form, SDA content, astaxanthin and GPR120 activation make it a fundamentally different supplement with a different biological profile. For dogs and cats with chronic inflammation, joint complaints or skin problems, calanus oil provides an omega-3 base that regular fish oil cannot match.
Calanus oil works best as part of a broader supplement protocol. It provides the systemic anti-inflammatory base. Targeted supplements for joints, skin or intestines supplement at the organ level.
Literature
- Höper AC, et al. Wax esters from the marine copepod Calanus finmarchicus reduce diet-induced obesity and obesity-related metabolic disorders in mice. J Nutr. 2014; 144(2):164-9.
- Cook CM, et al. Wax ester rich oil from the marine crustacean Calanus finmarchicus is a bioavailable source of EPA and DHA for human consumption. Lipids. 2016; 51(10):1137-1144.
- Scottish PC, et al. Possible health effects of a wax ester rich marine oil. Front Pharmacol. 2020;11:961.
- Oh DY, et al. GPR120 is an omega-3 fatty acid receptor mediating potent anti-inflammatory and insulin-sensitizing effects. Cell. 2010; 142(5):687-698.
- Gasmi A, et al. Calanus oil in the treatment of obesity-related low-grade inflammation, insulin resistance, and atherosclerosis. Appl Microbiol Biotechnol. 2020; 104(3):967-979.
- Vosskötter F, et al. Intake of Calanus finmarchicus oil for 12 weeks improves omega-3 index in healthy older subjects. Lipids. 2023; 58(3):129-138.
- NutraIngredients. EU increases higher daily intake limits for Zooca Calanus Oil. 2025. Based on: Lipidology. 2025; 2(2).
- Hands JM, et al. A multi-year rancidity analysis of 72 marine and microalgal oil omega-3 supplements. J Diet Suppl. 2024; 21(2):195-206.
- Hites RA, et al. Global assessment of organic contaminants in farmed salmon. Science. 2004;303:226-229.
- Jensen IJ, et al. An update on the content of fatty acids, dioxins, PCBs and heavy metals in farmed, escaped and wild Atlantic salmon in Norway. Foods. 2020; 9(12):1901.
- Sanden M, et al. Nutrients and contaminants in farmed Atlantic salmon fillet and fish feed from 2006 to 2021. ScienceDirect. 2025.
This information is educational in nature and based on available scientific literature. Calanus oil is intended as a dietary supplement for support and does not replace a veterinary consultation. In case of severe or persistent complaints, always consult a veterinarian.