Fish Oil vs Krill Oil: Which Should You Take?

Below we compare the two on EPA and DHA content, actual absorption, cost per gram of omega-3, the astaxanthin bonus, safety, and the one case where krill genuinely earns its price.

Fish oil vs krill oil: which is better?

For most people, fish oil is the better choice. It delivers far more EPA and DHA per capsule, costs much less per gram of omega-3, and sits on a far larger body of research. Krill oil is worth considering only if you want smaller pills, fewer fishy burps, the astaxanthin, and you do not mind paying more.

Both supply the two omega-3s that matter, EPA and DHA. The differences are in form, concentration, and price, not in whether they work. Once you compare them on usable omega-3 rather than marketing, the choice for most goals is straightforward.

Is krill oil really absorbed better than fish oil?

Not meaningfully, once the dose is matched. A 2015 study by Yurko-Mauro and colleagues gave 66 adults the same amount of EPA and DHA from fish oil or krill oil and found comparable blood and red blood cell omega-3 levels after four weeks.

Where the better-absorption claim comes from

Krill oil carries part of its omega-3s as phospholipids, while fish oil uses triglycerides or ethyl esters. Phospholipids are a natural part of cell membranes, so the theory is that they slip across the gut wall more easily.

Several early studies did report higher omega-3 levels from krill. The catch is that those studies often used a different dose or a different amount of EPA and DHA in each supplement, so they were comparing apples with oranges.

What matched-dose studies show

When the EPA and DHA dose is held equal, the gap closes. In the four-week study above, plasma and red blood cell omega-3 levels were similar across fish oil and krill oil formulations. Evidence suggests any absorption edge for krill is small and does not overcome its much lower concentration and higher price.

You can read the study on PubMed.

How much EPA and DHA does each actually contain?

Fish oil is far more concentrated. A typical fish oil softgel provides roughly 300 to 500 mg of combined EPA and DHA, while a typical krill oil capsule provides closer to 100 to 150 mg. The number that matters is the EPA and DHA on the supplement facts panel, not the total oil weight of the capsule.

This is where a lot of buyers get tricked. A “1,000 mg krill oil” capsule sounds substantial, but only a fraction of that is EPA and DHA. Always read the panel for the actual omega-3 content per serving, since fish oil products vary widely in concentration too.

How many capsules to reach a therapeutic dose?

Many heart-health studies use around 1 gram of combined EPA and DHA per day, though no official recommended amount has been set. To reach that from fish oil, you usually need 2 to 4 concentrated softgels. From krill oil, you may need 7 to 10 or more capsules, which is why most krill users fall short.

Most people take only 1 or 2 krill capsules daily. That provides some omega-3s, but often well below the amounts used in research. For a specific target, see our guide on how much fish oil to take.

Cost per gram of EPA and DHA, not per bottle

Krill oil almost always costs several times more per gram of actual omega-3. A bottle can look reasonable until you divide the price by the real EPA and DHA it delivers, at which point fish oil is dramatically cheaper for the same usable dose.

The fair way to compare any two omega-3 products is cost per gram of EPA and DHA, not price per bottle or per capsule. A cheaper-looking krill bottle that contains little omega-3 is not a saving, it just spreads a smaller amount of omega-3 across more expensive pills.

What about the astaxanthin in krill oil?

Astaxanthin is a real antioxidant, and it gives krill oil its natural red color. It is a genuine point in krill’s favor. But the amount in a normal krill dose is small, and there is no strong evidence that it makes krill better than fish oil for raising omega-3 levels.

If you specifically want astaxanthin, it is sold as its own inexpensive supplement. Paying a large omega-3 premium mainly to get a small dose of it, is not an efficient choice.

When is krill oil actually worth it?

Krill oil makes sense in a few specific cases. Outside of these, fish oil delivers more omega-3 for less money.

Smaller pills and fewer fishy burps

Krill capsules are often smaller and easier to swallow, and many people report fewer fishy burps and less aftertaste than with standard fish oil. If that has stopped you taking omega-3s at all, krill can be the version you will actually stick with.

If cost is not a concern

If price is not a factor and you like the idea of the phospholipid form plus the astaxanthin, krill is a perfectly good source of EPA and DHA. You are paying more per gram, but you are still getting real omega-3s.

A phospholipid preference

Some people simply prefer the phospholipid form on principle. The matched-dose evidence suggests it will not give you dramatically more omega-3, but it is a reasonable personal preference if you can afford it.

Is fish oil or krill oil safer?

Both are generally well tolerated. The clearest safety difference is allergy: krill is a crustacean, so anyone with a shellfish allergy should avoid it and use fish oil or an algae-based omega-3 instead. Both can cause mild digestive upset or fishy burps, and both may thin the blood slightly.

Because omega-3s can have a mild blood-thinning effect, it is worth talking to a doctor before high doses if you take blood thinners or have a bleeding condition. Anyone pregnant or managing a health condition should also check with a healthcare provider first. The NIH Office of Dietary Supplements notes that no formal EPA and DHA intake amount has been established.

What about algae oil?

Algae oil is the vegan omega-3. It supplies EPA and DHA directly from algae, the same source fish get their omega-3s from, which makes it a good fit for vegetarians, vegans, and anyone with a fish or shellfish allergy. It tends to be higher in DHA than EPA and can cost more per gram than fish oil.

For pure omega-3 content and price, fish oil still usually wins. But if you avoid seafood for dietary or allergy reasons, algae oil is the practical way to get EPA and DHA without relying on the small, unreliable conversion your body makes from plant-based ALA.

Fish oil vs krill oil: side by side

Which omega-3 should you take?

Choose fish oil for everyday use and for hitting a real therapeutic dose without swallowing a handful of pills or overpaying. Choose krill oil if smaller capsules and fewer burps are what get you to take it consistently, or if you want the phospholipid form and astaxanthin and cost is not an issue.

For vetted products, our guide to the best fish oil supplements breaks down specific picks by EPA and DHA content and value. If you are weighing a different pairing, see fish oil vs cod liver oil, which compares concentration against the added vitamins A and D.