Short answer: if you’re vegetarian or vegan, buy algae oil. It is the only source of marine-grade EPA and DHA that involves no animal at all, and we say that as a company that sells krill. For everyone else, the choice comes down to what’s actually in each oil, what a milligram of omega-3 costs from each, and one fact about the food chain that the krill industry — us included — doesn’t usually lead with. Here it is first.
Every omega-3 in a krill started out in an alga
Krill don’t make EPA and DHA. Nothing in the animal kingdom makes much of it. The molecules are built by microalgae at the bottom of the marine food chain, and everything above — krill, sardines, salmon, whales — gets its omega-3 by eating them, directly or several stomachs removed. Even the astaxanthin that makes krill oil deep red comes from the krill’s algal diet.
So the honest way to describe algae oil is this: it skips the middleman. Instead of waiting for a crustacean to concentrate the algae’s oil for you, you grow the algae and press the oil out of them directly. That is the single strongest argument for algae oil, and you’ll notice it’s a krill company telling you.
What algae oil actually is — a factory product, and for once that’s the point
Commercial algae oil mostly comes from Schizochytrium, a marine microorganism grown nowhere near the sea. It’s raised in closed stainless-steel fermenters, fed sugar in the dark — the commercial strains don’t even photosynthesize — then harvested and pressed. The UK’s food-safety regulator has assessed several of these strains as novel foods, which is how tightly defined the process is: named strain, defined feedstock, specified oil.
We spend a lot of time on this site saying “from a boat, not a factory.” Algae oil is from a factory in the most literal sense — and in this one comparison, that cuts in its favor. A closed tank has no fishery, no bycatch, no season, and no ocean-borne contaminants to worry about. It doesn’t touch the ocean at all.
The composition difference nobody puts on the front of the box
The two oils are not interchangeable milligram for milligram, and the difference isn’t the total — it’s the split.
Most algal oils are DHA-heavy. Some are DHA-only; the classic Schizochytrium strains produce mostly DHA, and strains with meaningful EPA are a newer development. Krill oil runs the other way: it’s EPA-forward, typically carrying substantially more EPA than DHA, and it arrives packaged in phospholipid form with its astaxanthin still aboard. Algal oil is a triglyceride oil, like ordinary fish oil.
The practical advice is the same one we give in every comparison we’ve written: turn the bottle over. Ignore the front-of-box number and read the EPA and DHA lines per softgel. Some algal products have an EPA line that reads zero. If you’re following research that leaned on EPA, that matters.
What the trials actually show for algae oil
The evidence for algal oil is real, and we’re not going to pretend otherwise.
The bioavailability question was settled back in 2008: Arterburn and colleagues randomized 32 adults to 600 mg of DHA a day from either algal-oil capsules or portions of cooked salmon for two weeks. Plasma phospholipid DHA rose about 80% in both groups. The capsules were nutritionally equivalent to eating the fish — for the nutrient measured. That’s about as clean a result as supplement science produces.
On blood lipids, a 2012 meta-analysis in the Journal of Nutrition pooled 11 randomized trials — 485 people, median dose 1.68 g of algal DHA a day — and found triglycerides down about 18 mg/dL, HDL up modestly, and LDL up about 9 mg/dL. If that LDL number sounds familiar, it’s the same caveat we published about krill and fish oil in our cholesterol article: omega-3s can pull triglycerides down and nudge LDL up at the same time. Algae oil doesn’t escape that; it’s the molecules, not the source.
Note the dose, though: 1.68 g a day is several softgels of any consumer product, algal or krill. The headline effects in the trials come from bigger doses than most labels suggest.
And the comparison you actually came here for — krill against algae, head to head, in a randomized trial? We looked. We could not find one. Both oils have been compared against fish oil in separate studies, and anyone who tells you one “absorbs better” than the other is extrapolating across trials that were never designed to meet. That includes us: the phospholipid form is a real absorption advantage on the evidence we have, and it is modest, not a multiplier.
What a milligram costs from each
ConsumerLab, which tests and prices these products independently, puts the cost of 500 mg of EPA+DHA at roughly 16–56¢ from fish oil, 48–61¢ from algal oil, and $1.38–$2.60 from krill oil. Krill — ours included — is the most expensive way to buy a milligram of omega-3. Algal sits in the middle. Fish is cheapest. We’ve published that before and it hasn’t stopped being true.
Sustainability: algae doesn’t just compete here — it wins
The Antarctic krill fishery is genuinely well managed — catch limits set by treaty, and in 2025 the fleet hit its trigger level for the first time and the fishery closed early, which is the system working, as we’ve written. But a well-regulated fishery is still a fishery. A fermentation tank has no catch limit because it has no catch. If your first filter is “no animal, no ocean impact,” this comparison is over before it starts, and algae oil is the answer.
A note on Captains
Captains Krill Oil™ is a whole, natural oil, pressed mechanically from fresh-caught Antarctic krill right on the boat — no chemicals at any stage, no shipping krill meal across the world to be reprocessed months later. It’s a natural catch that varies a little lot to lot; we test lots at random and they come back strong, and documentation is available on request. We’ve been doing it this way for 20 years.
But notice what none of that answers: the vegan question. If the reason you’re reading this is that you don’t eat animals, our process doesn’t matter — the krill does. No sourcing story changes what a krill is.
You might not need us
Three honest exits. If you’re vegetarian or vegan, buy algae oil — it’s the only option on this page that fits, and the DHA evidence behind it is solid. If you eat fatty fish twice a week, you likely don’t need either capsule; the salmon in the Arterburn trial performed exactly as well as the supplement it was tested against. And if you’re chasing grams of omega-3 for a triglyceride number, concentrated fish oil is the cheapest route per milligram — and at those doses it should be a conversation with your doctor, not a shelf decision.
If you eat fish, want an EPA-forward whole oil, and care how the thing was made, that’s the buyer we built Captains for.
Honest answer, not a pitch. — captainskrilloil.com
Quick answers
Is algae oil as good as krill oil?
For DHA, algal capsules proved nutritionally equivalent to cooked salmon in a randomized trial, which is a strong result. But the two oils differ in composition: algal oil is DHA-heavy and often low or zero in EPA, while krill oil is EPA-forward with phospholipids and astaxanthin. No head-to-head trial has compared them directly.
Does algae oil contain EPA?
It depends on the product. Classic Schizochytrium algal oils are mostly DHA, and some products contain no meaningful EPA at all; newer strains include both. Check the EPA line on the supplement facts panel rather than the front of the box.
Is krill oil vegan?
No. Krill are animals — small crustaceans — so no krill oil is vegan or vegetarian. Algae oil is the vegan source of marine EPA and DHA, made from microalgae grown in fermentation tanks.
Which is more sustainable, krill oil or algae oil?
Algae oil. It’s grown in closed fermenters on land with no fishery involved. The Antarctic krill fishery is tightly capped and regulated by treaty, and closed early in 2025 when it hit its trigger level — but a tank with no catch beats even a well-managed catch on ocean impact.
Can you take krill oil and algae oil together?
You can, but there’s rarely a reason to. Both deliver EPA and DHA, and your total intake is what matters. Pick one based on your diet, the EPA/DHA split you want, and what you’re willing to pay per milligram.