Fish oil vs algae oil: what’s the difference?

Fish oil comes from fish; algae oil comes from microalgae. Both can provide DHA and EPA. The source alone does not tell you how much a capsule or millilitre contains, what you pay for it or which test results are available. Those details need to be checked for the individual product.^[1]

The difference starts with the source

Fish oil is extracted from fish. Algae oil is extracted from cultivated microalgae. One example is Schizochytrium, a micro-organism used to produce oil rich in DHA and EPA.^[2]

The DHA and EPA in the fish food chain also originate in microalgae. Fish acquire these fatty acids through their food.^[3] The two oils therefore follow different production routes.

That does not make the finished supplements identical. The amounts of fatty acids, other ingredients and pack size also determine what you are buying.

The differences at a glance

This table compares characteristics. You still need the relevant product label or report to establish its declared composition and available measurements.

Does algae oil contain EPA?

There are algae oil supplements with DHA and EPA, and products that declare an amount of DHA only. “Algae oil” does not specify a fixed ratio between the two. Amounts also vary between fish oil supplements.^[3]

Check the individual entries for DHA and EPA, and the portion they refer to. An amount per two capsules can only be compared with an amount per capsule after both have been put on the same basis.

If EPA is missing from the label, that alone does not establish that none is present. Distinguish between an explicit declaration of zero and an amount that has not been stated. An exact DHA+EPA calculation requires both amounts or an explicitly declared combined total.

For a closer look at those entries, see How to read an omega-3 supplement label.

Is algae oil the same as other plant-based omega-3?

“Plant-based omega-3” does not identify the fatty acid. Flaxseed oil, for example, is a source of ALA. That is a different omega-3 fatty acid from DHA or EPA.^[1]

Algae oil can contain DHA and EPA. Milligrams of ALA from another oil cannot be entered as milligrams of DHA+EPA. Products containing only ALA should therefore remain outside a price comparison based on DHA+EPA.

“Total omega-3” is not automatically equal to DHA+EPA either: the total may include other omega-3 fatty acids.

Is an algae oil supplement always vegan?

The source of the oil and the composition of the whole supplement are separate questions. For capsules, that includes the shell.

Check the complete ingredients list and any manufacturer information about ingredient origins. Gelatine, for example, is animal-derived.^[4] The word “algae oil” on the front of the pack does not describe the other ingredients.

If an ingredient’s origin is unclear, that remains an open question. Do not infer the capsule-shell composition from the oil source.

How do you compare prices?

The pack price and capsule count do not establish what you pay for the amount of DHA+EPA. You also need the composition per capsule. For liquid oils, use the amount per millilitre.

The calculation works for fish oil and algae oil. It is a price based on the declared contents. An equal DHA+EPA total does not mean that the individual amounts of DHA and EPA are equal.

Compare products within the same composition group as well. A product with added vitamin D or Q10 has a different composition from one without those additions. When comparing current shop offers, check the observation date, delivery charges and any promotional conditions too.

What does the source establish about freshness and contaminants?

A statement about the measured contents of a particular batch needs a report that applies to it. The words “fish oil” or “algae oil” alone do not establish those measurements.

Check which product and batch were examined. Does the report concern the ingredient oil or the finished supplement? Which properties and contaminants were measured, using which method and on what date?

A TOTOX result concerns oxidation of the oil examined. It does not replace a measurement of DHA+EPA content or testing for contaminants.^[6] Nor should a result be extended to other batches or another oil type without supporting evidence.

If no public report can be found, the publicly available results for that product or batch remain unknown. That does not establish that the product was not tested.

Is algae oil more sustainable than fish oil?

Comparing environmental impacts takes more than an oil’s name. Life cycle research shows that production methods, feedstocks and the environmental measure being assessed can change the comparison.^[5]

A comparison of aquaculture feed ingredients is also not a direct comparison of two retail supplements. Check exactly what a study compares and which stages it includes. A conclusion about one production process does not automatically apply to every product using the same oil source.

Comparing fish oil and algae oil on SUPPFAX

SUPPFAX lets you compare the oil source, label information and available Netherlands shop prices. The price per gram of DHA+EPA puts different pack sizes on the same basis.

Also check the individual DHA and EPA amounts, other ingredients and sources attached to the product. These answer different questions; the oil source alone cannot summarise them.

Sources

Consulted on 31 October 2026.

1. NIH Office of Dietary Supplements — Omega-3 Fatty Acids, consumer fact sheet. For oil sources and the distinction between DHA, EPA and ALA. ↩ ↩
2. EFSA — DHA- and EPA-rich oil from Schizochytrium, 2014. For one documented microalgae source; not evidence about an individual supplement. ↩
3. NIH Office of Dietary Supplements — Omega-3 Fatty Acids, health professional fact sheet. For microalgae in the food chain and differences between supplement formulations. ↩ ↩
4. Regulation (EC) No 853/2004, Annex I, point 7.7. For the animal origin of gelatine. ↩
5. Life cycle study of Schizochytrium and fish oil in aquaculture feeds, 2022. For differences between production processes and environmental measures; the study does not compare finished consumer supplements. ↩
6. Codex Alimentarius — Standard for Fish Oils, CXS 329-2017. For the distinction between oxidation parameters, fatty-acid composition and contaminants in fish oils; not general comparability of TOTOX across all oil sources. ↩