Two glass bottles of amber omega-3 capsules beside fresh whole sardines and krill on a wooden board in natural window light

Fish Oil vs Krill Oil: Which Omega-3 Is Right for You?

Quick answer: Fish oil and krill oil both supply EPA and DHA, the two omega-3 fatty acids most studied for heart, joint, and brain support. Fish oil gives you more EPA and DHA per capsule at a lower cost. Krill oil delivers omega-3s in a phospholipid form and adds astaxanthin, a natural antioxidant, but provides less EPA and DHA per capsule and costs significantly more. For most people who want to meet a specific EPA and DHA target, fish oil is the practical starting point. Krill oil may be worth considering if you prefer a smaller capsule and do not have a shellfish allergy, but the research on absorption advantage over fish oil is mixed and not settled.

What Are Fish Oil and Krill Oil?

Both supplements come from marine sources and are prized for their omega-3 fatty acid content, specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Beyond that shared purpose, they differ in origin, composition, and cost.

Fish oil is extracted from the tissue of oily fish such as anchovies, sardines, mackerel, and herring. It is the most widely studied source of marine omega-3s and typically delivers 300 to 600 mg or more of combined EPA and DHA per softgel, depending on concentration and serving size.

Krill oil is extracted from krill, tiny shrimp-like crustaceans found in cold ocean waters. The omega-3s in krill oil are bound primarily to phospholipids rather than the triglycerides found in most fish oil. Krill also naturally contains astaxanthin, a carotenoid antioxidant that gives krill its red color and may help protect the fragile omega-3 fatty acids from oxidation.

To understand why EPA and DHA matter in the first place, see our broader overview: Omega-3 and Fish Oil Benefits.

Fish Oil vs Krill Oil: Side-by-Side Comparison

Feature	Fish Oil	Krill Oil
EPA and DHA per capsule	Typically 300 to 600 mg combined (higher in concentrated products)	Typically 100 to 200 mg combined
Omega-3 molecular form	Primarily triglycerides (re-esterified in quality products)	Primarily phospholipids
Astaxanthin content	None unless added separately	Naturally present
Absorption evidence	Well established; triglyceride form absorbs well taken with food	Phospholipid form may absorb efficiently; human comparison data at equal doses are mixed
Cost per mg EPA and DHA	Lower	Considerably higher
Capsule size	Often larger softgels	Often smaller capsules
Fishy aftertaste or burps	Common with standard products; reduced with enteric coating	Less commonly reported
Allergy risk	Fish allergy consideration	Shellfish allergy consideration
Sustainability considerations	Varies by fishery; look for MSC certification	Antarctic fishery is well regulated; look for certification labels

Does Krill Oil Absorb Better Than Fish Oil?

This is the most marketed claim for krill oil, and the science is more nuanced than many ads suggest.

Krill oil proponents argue that because omega-3s in krill are bound to phospholipids (the same structural molecule that makes up cell membranes), they may be absorbed more efficiently and might not require food for good uptake. Some smaller studies have reported higher blood levels of EPA and DHA after krill oil consumption compared with an equal nominal dose of fish oil.

However, several important caveats apply:

Many comparison studies did not match the actual EPA and DHA dose between groups, making it difficult to isolate a true form advantage.
When researchers account for the actual EPA and DHA dose delivered rather than total milligrams of oil, the absorption difference largely narrows or disappears.
Fish oil taken with a fat-containing meal already absorbs well. Enteric-coated fish oil further improves tolerability without sacrificing absorption.
Larger, longer human trials comparing clinical outcomes between the two forms are limited.

The practical takeaway: krill oil is not clearly superior in absorption once you control for equal EPA and DHA doses. Both forms can meaningfully raise blood omega-3 levels when taken correctly.

Krill Oil Benefits: What Does the Research Actually Support?

Because krill oil contains EPA and DHA, it shares the same research areas as fish oil, including cardiovascular health markers, joint comfort, and cognitive function. Research suggests omega-3s from krill may support healthy triglyceride levels and joint comfort similarly to fish oil when doses of EPA and DHA are matched.

Krill also contains astaxanthin, which is studied separately for antioxidant activity. However, the amount of astaxanthin in a typical krill oil capsule is modest, and it is not on its own a strong reason to choose krill over fish oil if your primary goal is omega-3 intake.

For a detailed look at what the omega-3 research covers, see: Omega-3 and Fish Oil Benefits.

The Dose Problem with Krill Oil

This is where the practical decision becomes clear.

A standard krill oil capsule typically delivers 100 to 200 mg of EPA and DHA combined. A quality fish oil softgel commonly delivers 500 mg or more. If a target of 1,000 mg of combined EPA and DHA per day is your goal, a range commonly discussed in cardiovascular research contexts, you may need five to ten krill oil capsules to reach it versus two quality fish oil softgels. At the premium price krill oil commands, that difference adds up quickly.

This does not make krill oil worthless. But it does mean label reading is essential. Always check the supplement facts panel for EPA and DHA milligrams specifically, not just the total "fish oil" or "krill oil" milligrams. Total oil weight and actual EPA plus DHA content are very different numbers.

For a deeper look at dosing and what research says about amounts, see our guide: Fish Oil Dosage: How Much Should You Take?

Allergy and Safety Considerations

Allergy is a genuine and important differentiator between the two supplements:

Fish allergy: People with a fish allergy should avoid standard fish oil supplements. Check with your allergist before using any fish-derived product.
Shellfish allergy: Krill is a crustacean. Anyone with a shellfish allergy should avoid krill oil and discuss alternatives with their healthcare provider.

Other safety considerations apply to both supplements:

Blood thinners and anticoagulants: Higher doses of omega-3s may affect platelet function. If you take warfarin, aspirin therapy, or other anticoagulants, talk with your doctor before adding either supplement.
Blood pressure medications: Omega-3s can modestly support healthy blood pressure levels, which could interact with certain medications. Let your prescriber know what you are taking.
Upcoming surgery: Some surgeons ask patients to pause omega-3 supplements before elective procedures. Follow your surgical team's guidance.
AFib (atrial fibrillation): Higher-dose prescription omega-3s have been studied in the context of AFib risk. If you have AFib or are at elevated risk, discuss omega-3 supplementation with your cardiologist.
Pregnancy and breastfeeding: DHA is important for fetal brain and eye development. Pregnant and breastfeeding individuals should discuss omega-3 supplementation with their OB or midwife to determine appropriate type and amount.

For a full picture of interactions and side effects, see: Fish Oil Side Effects and Interactions.

Sustainability: Is One More Eco-Friendly?

Both fish oil and krill oil come with sustainability considerations, and neither is a clear winner for every consumer.

Fish oil sustainability depends heavily on the fishery. Products certified by the Marine Stewardship Council (MSC) or sourced from well-managed small pelagic fisheries (anchovies, sardines, herring) are generally considered responsible choices. Less carefully sourced fish oil can contribute to overfishing of these species.

Krill oil is most often sourced from Antarctic krill, a fishery that is generally well-regulated with harvest limits designed to protect the broader Antarctic ecosystem, including penguins, seals, and whales that depend on krill as a food source. Some environmental groups raise concerns about expanding krill harvests as supplement demand grows.

If sustainability matters to you, look for certification labels on either type of product and check the brand's sourcing disclosures directly.

What the VITAL and REDUCE-IT Trials Tell Us

Two large clinical trials are frequently cited in omega-3 discussions. Understanding what each one actually studied helps put supplement claims in context.

The VITAL trial tested approximately 1 gram per day of omega-3s in a large general adult population with no prior cardiovascular disease. It did not significantly reduce major cardiovascular events overall, though some subgroup analyses suggested possible benefit in certain populations. This was a standard, over-the-counter-style dose given to people at average cardiovascular risk.

The REDUCE-IT trial tested 4 grams per day of icosapent ethyl, a purified prescription EPA drug (not a fish oil supplement), in people with elevated triglycerides who were already on statin therapy. It did significantly reduce cardiovascular events. The results from a high-dose purified prescription drug cannot be applied directly to over-the-counter fish oil or krill oil supplements.

Neither trial used krill oil. Both inform our understanding of omega-3s, but neither settles the fish oil versus krill oil question on its own.

How to Choose Between Fish Oil and Krill Oil

Choose fish oil if:

You want the most EPA and DHA per dollar spent
You want to align with the dose ranges most commonly used in clinical research
You do not have a fish allergy
Fishy aftertaste is a concern (look for enteric-coated softgels)

Consider krill oil if:

You prefer a smaller capsule and are not concerned about taking more of them to reach your dose
You have a fish (finfish) allergy but not a shellfish allergy (always confirm with your allergist first)
You want the astaxanthin that naturally comes along with krill
Budget is not a significant factor in your decision

Regardless of which you choose:

Read the label for EPA and DHA milligrams, not total oil weight
Look for third-party purity testing certificates (heavy metals, PCBs)
Take with a meal containing dietary fat to support absorption
Talk with your doctor if you take medications or have a chronic health condition

For more on evaluating quality and reading labels, see: How to Choose a Fish Oil Supplement and our timing guide at Best Time to Take Fish Oil.

A Note on Fish Oil Purity and Testing

If you are evaluating fish oil options, Me First Living Omega-3 Fish Oil provides 800 mg EPA and 400 mg DHA per two-softgel serving (2,000 mg total fish oil), uses enteric coating to reduce fishy aftertaste, and is molecularly distilled and batch-tested for heavy metals, salmonella, E. coli, and mold with a Certificate of Analysis. It is made in an FDA-regulated, GMP-certified facility and is free of gluten, lactose, artificial colors, and artificial flavors. Directions are two softgels per day with or before a meal, and it comes with a 60-day satisfaction guarantee.

Omega-3s are also often used alongside other nutrients studied for inflammation and cardiovascular support. For context on complementary options, see our articles on turmeric benefits, turmeric and heart health, and cinnamon and omega-3.

Key Takeaways

Fish oil and krill oil both provide EPA and DHA, but fish oil delivers significantly more per capsule at a lower cost per milligram.
Krill oil omega-3s are in phospholipid form and include natural astaxanthin; evidence for a meaningful absorption advantage over fish oil at equal doses is mixed.
To reach a specific daily EPA and DHA target, you will likely need considerably more krill oil capsules, which raises cost substantially.
Fish allergy contraindicates fish oil; shellfish allergy contraindicates krill oil. Always check with your allergist.
Both supplements require caution if you take blood thinners or blood pressure medications, ahead of surgery, with AFib, or during pregnancy.
Sustainability credentials vary by brand and fishery for both types. Look for third-party certification.
Always read the supplement facts label for EPA and DHA milligrams specifically, not just total oil weight.
For most adults, a high-quality enteric-coated fish oil is the practical, cost-effective first choice for omega-3 supplementation.

This article is for educational purposes and isn't medical advice. Talk with your healthcare provider about your individual needs.

Frequently Asked Questions

Is krill oil better than fish oil?

Not clearly for most people. Krill oil has some unique properties including a phospholipid omega-3 form and natural astaxanthin, but it provides much less EPA and DHA per capsule than most fish oil products. At equal EPA and DHA doses, the human evidence for a meaningful absorption advantage is mixed. Fish oil offers more omega-3s per dollar. The better choice depends on your budget, allergy status, and dosing goals.

Can I take krill oil if I have a shellfish allergy?

You should not take krill oil without first speaking with your allergist or doctor. Krill is a crustacean, and krill oil may trigger reactions in people with shellfish allergies. Fish oil from finfish may be an alternative, but individual allergy profiles vary and need professional evaluation before you make the switch.

How much EPA and DHA is in a typical krill oil capsule?

Most standard krill oil capsules provide 100 to 200 mg of combined EPA and DHA. By comparison, a quality fish oil softgel often delivers 300 to 600 mg or more. If you are aiming for 1,000 mg of combined EPA and DHA daily, you may need five to ten krill oil capsules versus two quality fish oil softgels. Always check the supplement facts panel for EPA and DHA figures specifically, not total oil weight.

Does krill oil cause fishy burps like fish oil?

Krill oil is less commonly associated with fishy burps or aftertaste compared with standard fish oil. However, enteric-coated fish oil softgels are designed to dissolve in the small intestine rather than the stomach, which reduces this problem significantly for most people. If fishy burps have put you off fish oil before, an enteric-coated product is worth trying before switching to krill.

Is krill oil worth the extra cost?

For most people, no, unless there is a specific reason such as preferring a smaller capsule, wanting astaxanthin from a single product, or managing a fish allergy without a shellfish allergy. The cost per milligram of EPA and DHA from krill oil is considerably higher than from fish oil. If budget matters, a quality fish oil provides more omega-3s per dollar.

When should I take fish oil or krill oil?

Both are best absorbed when taken with a meal that contains some dietary fat. Splitting the dose across two meals may improve absorption and reduce digestive discomfort. For a detailed look at timing, see: Best Time to Take Fish Oil.

Are fish oil and krill oil safe for long-term use?

Both have been used in research studies lasting months to years without major safety signals at typical supplement doses. The main cautions involve potential blood-thinning effects at higher doses, interactions with certain medications, allergy risk, and specific considerations for people with heart conditions or who are pregnant. Talk with your healthcare provider before starting long-term supplementation, especially if you take prescription medications.