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Most people who take fish oil have never asked how fish oil is made. It arrives in a capsule, it's supposed to be healthy, and that's usually where the investigation stops. But the journey from ocean to supplement is more complicated — and more problematic — than most brands want you to know. Understanding how fish oil is made reveals why the production process matters for both your health and the planet.
Here's the full picture.
A brief history of fish oil
Fish have been part of the human diet for thousands of years. Ancient Romans consumed crude fish oil for its supposed medicinal properties. But it wasn't until the 1970s that scientists began seriously studying omega-3 fatty acids, after researchers noticed that native Inuit people — despite eating diets extremely high in fatty fish — had surprisingly low rates of heart disease.
That research led to the widespread understanding that EPA and DHA, two specific omega-3 fatty acids found in fatty fish, play important roles in heart health, brain function, and inflammation. The fish oil supplement industry followed.
Today fish oil is one of the most commonly taken dietary supplements in the world. That level of demand has consequences.
How fish oil is made: step by step
The production process for fish oil is lengthy, energy-intensive, and takes the oil through multiple countries before it reaches a capsule.
Step 1 — FishingOily, cold-water fish like anchovies, sardines, and mackerel are caught in large quantities. These are primarily "reduction fisheries" — fish caught specifically to be processed into oil and fishmeal, not for direct human consumption. Roughly 50 fish are used per bottle of omega-3 supplement.
Step 2 — Cooking and pressingThe whole fish are cooked down at high temperatures to separate the oil from the protein and water. This is called the "wet pressing" method. The result is crude fish oil — dark, smelly, and far from the finished product.
Step 3 — ExtractionSome producers also use chemical solvents — including chloroform and methanol — to extract additional oil from the remaining fish material. These solvents must then be removed in later processing stages.
Step 4 — Shipping for refiningThe crude oil is then shipped — often internationally — to refineries. This is the first of several long-distance transportation legs in the production chain.
Step 5 — RefiningAt the refinery, the crude oil goes through multiple chemical processes:
- Degumming — removes phospholipids
- Bleaching — removes colour and some contaminants
- Deodorising — removes the strong fishy smell using high heat
- Deacidification — neutralises free fatty acids
Each of these steps involves heat, chemicals, or both — and each one has the potential to degrade the omega-3 content and increase oxidation.
Step 6 — Concentration and encapsulationThe refined oil is then concentrated to increase EPA and DHA levels, mixed with antioxidants to slow rancidity, and encapsulated into softgels. This typically happens at a separate facility.
Step 7 — More shippingThe finished capsules are packaged and shipped to distributors, then to retailers, then to you.
By the time fish oil reaches your shelf, it may have crossed multiple continents.
Why the production process is a problem
Quality degradation
Omega-3 fatty acids are chemically unstable. They are particularly prone to oxidation — the same process that makes cooking oil go rancid. Every step of the production process that involves heat, light, air, or chemical exposure accelerates oxidation.
Studies have found that a significant proportion of commercially available fish oil supplements show measurable oxidation — meaning the oil has begun to degrade before it's even opened. Oxidised fish oil doesn't just lose its health benefits; research suggests it may actually promote inflammation rather than reducing it.
The "fish burps" many people experience after taking fish oil capsules are often a sign of oxidation and poor quality — not just an inevitable side effect of the supplement.
Contamination risk
Fish accumulate toxins from the water they live in, including heavy metals like mercury, PCBs, and dioxins. While the refining process is designed to remove these, the effectiveness varies significantly between producers. Quality control in the fish oil supplement industry is inconsistent.
You may not be getting what you paid for
The multiple processing stages can also affect the final EPA and DHA content. What's on the label may not accurately reflect what your body actually absorbs, particularly if the oil has oxidised during production or storage.
The environmental cost
Overfishing
The fish oil industry depends on reduction fisheries — large-scale industrial fishing operations that target small forage fish like anchovies and sardines. These fish are foundational to ocean food chains. Removing them in large quantities disrupts ecosystems that depend on them, from larger fish to seabirds to marine mammals.
Fisheries scientists have flagged the reduction industry as a significant contributor to the global fish stock crisis. As demand for omega-3 supplements grows, so does the pressure on these populations.
Fish farming doesn't help
Farmed fish are often raised on fishmeal and fish oil themselves — meaning they add to the demand for wild-caught fish rather than reducing it. Fish farms near coastal areas also risk polluting surrounding waters and introducing disease to wild fish populations.
Carbon footprint
The multi-stage, multi-country production process for fish oil generates substantial carbon emissions at every step — from the fishing boats to the refinery transportation to the distribution chain. For a supplement marketed as a health product, the environmental footprint is considerable.
A better source: algae oil
Here's the thing: fish don't make their own omega-3s. They get EPA and DHA by eating algae. Algae is the original source of omega-3s in the marine food chain.
Taking algae oil supplements cuts out all the intermediary steps — and most of the problems.
No fishing. Algae oil is grown indoors, in controlled environments, without touching the ocean. No overfishing. No ecosystem disruption.
No chemical solvents. High-quality algae oil is processed using only water — no chloroform, no methanol, no chemical extraction.
Lower oxidation risk. Because algae oil doesn't go through the same multi-stage refining process as fish oil, it's less exposed to the heat and chemical processes that promote oxidation.
No heavy metals. Algae grown in controlled indoor environments doesn't accumulate the ocean contaminants that fish do.
Same EPA and DHA. Studies confirm that algae oil provides the same omega-3 fatty acids in bioavailable form — your body absorbs them just as effectively.
Calgee's vegan omega-3 is made from algae grown indoors in North Carolina, processed only with water. Each serving delivers 300mg DHA and 150mg EPA in carrageenan-free, sorbitol-free tapioca softgels. Third-party tested by Eurofins Scientific. Carbon-negative packaging.
Shop Calgee Vegan Omega-3 on Amazon →
Frequently Asked Questions
What fish is fish oil made from?Most commercial fish oil comes from small, oily cold-water fish — primarily anchovies, sardines, mackerel, herring, and menhaden. These are caught in large quantities through industrial reduction fisheries, not for direct human consumption.
Is fish oil manufacturing regulated?In the US, dietary supplements including fish oil are regulated by the FDA under DSHEA (Dietary Supplement Health and Education Act), but the standards are less stringent than for pharmaceuticals. Third-party testing is the most reliable way to verify quality.
Why does fish oil smell so fishy?Fresh fish oil actually has a relatively mild smell. Strong fishiness is usually a sign of oxidation — the oil has begun to go rancid. High-quality fish oil that has been properly processed and stored should not smell strongly.
Can fish oil go bad?Yes. Fish oil is particularly susceptible to oxidation, which causes rancidity. Signs include a strong fishy or paint-like smell, dark colour, and a bitter taste. Oxidised fish oil should be discarded — consuming rancid fats may be harmful.
Is algae oil as effective as fish oil?Yes. Multiple studies confirm that algae oil provides EPA and DHA in a form that is well absorbed by the body — comparable to fish oil. As the original source of omega-3s in the marine food chain, algae is where fish get their EPA and DHA in the first place.
Is algae oil vegan?Yes. Algae oil is entirely plant-based and suitable for vegans and vegetarians. Fish oil is not.
How is Calgee's algae oil different from fish oil?Calgee's omega-3 is made from algae grown indoors in North Carolina, processed only with water (no chemical solvents), and third-party tested by Eurofins Scientific. It's carrageenan-free, sorbitol-free, and packaged in carbon-negative pouches made from sugarcane.
These statements have not been evaluated by the Food & Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
