The most useful information on a fish oil label is the amount of EPA and DHA per serving, not the total fish oil number. Many labels list a large milligram amount for the oil itself, but a much smaller number for the two omega-3 fats your body actually uses.
Once you know how to find that number, the rest of the label is easier: the form of the oil, a Health Canada licence number, and a few freshness clues. This guide walks through each one so you can compare products fairly.
Total fish oil vs. EPA and DHA: the number that matters
A bottle might say '1,000 mg fish oil' in large letters, but that is the weight of the whole oil, including fats your body does not use for the same purposes. Flip to the Supplement Facts panel and look for 'EPA' and 'DHA' listed separately, usually in milligrams.
Add the EPA and DHA numbers together to get the total omega-3 amount per serving. Two products that both say '1,000 mg fish oil' can have very different combined EPA and DHA content, so this is the real basis for comparison.
We cover how much EPA and DHA adults typically look for in a separate guide on omega-3 basics, since there is no official Canadian reference value for these two fats specifically.
- Find the Supplement Facts panel, not just the front-of-bottle claim
- Look for 'EPA' and 'DHA' listed in milligrams, not just 'omega-3' or 'fish oil'
- Add EPA and DHA together for the total active omega-3 amount
- Check how many softgels make up one serving, since some labels use two-capsule servings
Understanding the oil form: triglyceride, ethyl ester, or reformed
Fish oil comes in a few chemical forms, and the label sometimes states which one is used. This affects how concentrated the oil can be and how it is absorbed, though individual response varies.
Natural triglyceride form is close to how omega-3s exist in fish, but it is harder to concentrate to very high EPA and DHA levels. Ethyl ester form allows for higher concentration and is common in higher-strength products. Re-esterified triglyceride form starts as ethyl ester and is converted back to a triglyceride-like structure.
| Form | What it means | Typical use |
|---|---|---|
| Natural triglyceride (TG) | Closest to the form found in fish | Standard-strength fish oil |
| Ethyl ester (EE) | Processed to allow higher concentration | High-strength or high-dose products |
| Re-esterified triglyceride (rTG) | Ethyl ester converted back to triglyceride form | Premium or higher-strength products |
Check for a Health Canada licence number (NPN)
Natural health products sold legally in Canada, including fish oil, are supposed to carry a Natural Product Number (NPN) or a Homeopathic Medicine Number on the label. This number means the product has been reviewed by Health Canada for safety, quality, and label accuracy.
You can look up an NPN in the Licensed Natural Health Products Database to confirm what the product is licensed to contain and claim. If a fish oil bottle has no NPN at all, that is worth asking a pharmacist about before buying.
Freshness clues: smell, oxidation, and storage
Fish oil is a fat that can go rancid over time, especially once a bottle is opened. Rancid fish oil often has a strong, sour, or 'old fish' smell that is stronger than the normal mild fishy scent of fresh oil.
Labels usually list an expiry date and storage instructions, such as keeping the bottle in a cool, dark place or refrigerating after opening. Following these instructions helps the oil stay fresh for as long as the label suggests.
Some brands mention third-party testing for purity or freshness on the label or their packaging. This is a reasonable extra reassurance, though it is not required by Health Canada the way the NPN system is.
- A strong sour or rancid smell means the oil should be replaced
- Store in a cool, dark place, and refrigerate after opening if the label says to
- Note the expiry date and try to use the bottle before then
- Third-party testing claims are a bonus, not a substitute for an NPN
Other label details worth a quick look
Some fish oil labels mention the fish species used, such as anchovy, sardine, or salmon, along with where the fish was sourced. This is mainly useful if you have a personal preference around sustainability or want to avoid a specific fish for allergy reasons.
If you are choosing between fish oil, krill oil, and algae oil, the label comparison points differ slightly between them; we go through those differences in a separate article. For fish oil specifically, the points above (EPA and DHA amount, form, NPN, and freshness) cover what matters most.
People with a fish or shellfish allergy, those taking blood thinners, and pregnant or breastfeeding people should check with a pharmacist or doctor before starting a fish oil supplement, since interactions and individual needs vary.
The short version
- Look at the EPA and DHA milligrams per serving, not just the total fish oil weight.
- The oil form (triglyceride, ethyl ester, or re-esterified triglyceride) affects concentration and can affect absorption.
- A Health Canada NPN means the product has been reviewed for safety and label accuracy.
- Check the smell, expiry date, and storage instructions to judge freshness.
- Ask a pharmacist if you take blood thinners, are pregnant or breastfeeding, or have a fish allergy.
Shop the products
Frequently asked questions
What does '1,000 mg fish oil' actually mean on a label?
That number is the total weight of the oil in the capsule, not the amount of active EPA and DHA. Check the Supplement Facts panel for the separate EPA and DHA milligram amounts to know what you are really getting.
Is a higher EPA and DHA number always better?
A higher combined EPA and DHA amount means a more concentrated product, but the right amount depends on your personal goals and any advice from your doctor or pharmacist. There is no single official target amount for EPA and DHA in Canada.
Does fish oil need to be refrigerated?
Check the label, since this varies by product. Many brands recommend refrigeration after opening to slow down oxidation and help the oil stay fresh.
Why does my fish oil smell bad?
A mild fishy scent is normal, but a strong sour or rancid smell usually means the oil has started to oxidize and should be replaced. Proper storage in a cool, dark place, and refrigeration after opening if recommended, helps prevent this.
What is an NPN and why does it matter for fish oil?
An NPN is a Natural Product Number that shows Health Canada has reviewed the product for safety, quality, and accurate labelling. You can confirm details about a licensed product through the Licensed Natural Health Products Database.
Keep reading
- Omega-3 Explained: EPA, DHA and How Much You Need
- Fish Oil vs Krill Oil vs Algae Oil: How to Choose
- CoQ10: Ubiquinone vs Ubiquinol Explained
- Heart Health Basics: Where Supplements Really Fit In
Sources
- NIH Office of Dietary Supplements: Omega-3 Fatty Acids
- Health Canada: Licensed Natural Health Products Database
- Health Canada: About the Licensed Natural Health Products Database
- NCCIH: Using Dietary Supplements Wisely
This article is for general information only and is not medical advice. Talk to your doctor or pharmacist before starting a supplement, especially if you are pregnant or breastfeeding, take medication, or have a health condition.