How Much Fish Do You Need to Eat to Get Enough Omega-3?

November 23, 2025 •

4 min read

According to a 2024 analysis, many adults in the U.S. fall short of the recommended intake for crucial EPA and DHA omega-3 fatty acids. So, how much fish do you need to eat to get enough omega-3 for optimal health? The answer depends on your specific needs, fish type, and frequency.

Quick Summary

To get adequate EPA and DHA, aim for two servings of fatty fish per week, balancing your choices for omega-3 content and mercury levels. Alternative sources like algae-based supplements and plant options are also available.

Key Points

Two Servings Per Week: The general recommendation for most adults is at least two 3.5 to 4-ounce servings of fish per week, with at least one serving being oily fish.
Prioritize Oily Fish: Oily fish like salmon, sardines, and mackerel are the best dietary source of the beneficial EPA and DHA omega-3s.
Mind Mercury Levels: Choose low-mercury fish, such as sardines and salmon, and limit intake of high-mercury species like swordfish and large tuna, especially for vulnerable populations.
Inefficient ALA Conversion: Plant-based ALA omega-3s from sources like flaxseed are not efficiently converted into EPA and DHA by the body, making marine sources or supplements more effective.
Algae-Based Supplements: Vegans and individuals avoiding fish can consider algae-based supplements for a direct source of EPA and DHA, bypassing the need for inefficient conversion.
Holistic Benefits: Eating whole fish offers a broader spectrum of nutrients beyond just omega-3s, including protein, Vitamin D, and minerals, which supplements may lack.

The Foundation: Weekly Recommendations

Health organizations worldwide provide clear guidance on fish consumption to ensure adequate intake of marine-derived omega-3s, specifically EPA and DHA. The American Heart Association recommends that most adults aim for at least two servings of fish, particularly fatty fish, per week. A standard serving size is about 3.5 to 4 ounces (approximately 100-113 grams) cooked. This translates to about 8 ounces of fish per week to support heart health and other functions. Choosing oily fish is key, as they are the primary source of the most biologically available forms of omega-3. One important consideration is that the omega-3 content of farmed fish has been declining, meaning that the amount of fish required for the same level of omega-3 may have increased over time compared to wild-caught fish.

Why Not All Omega-3s Are Equal

Omega-3 fatty acids exist in three primary forms: Alpha-linolenic acid (ALA), Eicosapentaenoic acid (EPA), and Docosahexaenoic acid (DHA). ALA is found in plant sources like flaxseeds and walnuts. While the body can convert ALA into EPA and DHA, the conversion rate is very low and inefficient, often as low as 4-8%. For this reason, direct intake of EPA and DHA from marine sources is recommended for optimal health. EPA is known for its anti-inflammatory effects and cardiovascular benefits, while DHA is a crucial component for brain and eye health. This difference explains why simply consuming large quantities of nuts and seeds won't provide the same benefits as eating fatty fish.

Prioritizing High Omega-3 Fish, Low in Mercury

Not all fish are created equal when it comes to omega-3 content. Oily fish, which store the fatty acids throughout their body, are the best source. However, larger, predatory fish higher up the food chain tend to accumulate more mercury, a neurotoxin that can be harmful in high amounts, especially for pregnant women and young children. Therefore, selecting smaller, oilier fish is a smart strategy.

Here are some of the best choices for high omega-3 content with lower mercury levels:

Salmon: Both wild and farmed salmon are excellent sources of EPA and DHA, and a single serving can provide a significant portion of your weekly needs.
Sardines: These small, inexpensive fish are packed with omega-3s and are generally considered a low-mercury option due to their size.
Mackerel: Atlantic and Pacific mackerel are great sources of omega-3s.
Trout: Freshwater trout is a solid option, offering good omega-3 levels with low mercury.
Anchovies: Tiny but mighty, anchovies deliver a strong dose of omega-3s.

A Comparison of Oily Fish

To make informed choices, it's helpful to compare various fish based on their omega-3 content and potential mercury risk. The following table provides a simplified overview, noting that specific nutritional values can vary based on the fish's origin, diet, and preparation.


Fish Type (per 4 oz)	Omega-3 Content (EPA + DHA)	Mercury Risk	Recommendation
Wild Salmon	Very High (up to 2,000+ mg)	Low	Excellent choice for maximum benefit.
Sardines (Canned)	High (up to 1,500+ mg)	Low	Inexpensive, convenient, and nutrient-dense.
Atlantic Mackerel	High (up to 1,000+ mg)	Low	Great option, but check source for sustainability.
Trout	High (500-1,000 mg)	Low	Another reliable, low-mercury source.
Albacore Tuna (Canned)	Moderate (around 500 mg)	Higher	Limit intake, especially for sensitive groups.
Swordfish	High (around 1,000 mg)	Very High	Avoid due to high mercury levels.

The Role of Supplements and Plant-Based Alternatives

For those who do not eat fish or need higher therapeutic doses, supplements are a viable option. Fish oil supplements provide concentrated EPA and DHA, and algae-based supplements offer a vegan alternative, as algae is the original source of these fatty acids in the marine food chain. However, it is important to note that supplements may not provide all the synergistic nutrients found in whole fish, such as selenium and iodine. Always consult a healthcare provider before starting supplements, especially at higher dosages, as they can interact with medications.

For vegetarians and vegans relying on plant-based ALA, a good omega-6 to omega-3 ratio in the diet is important for maximizing the conversion rate. Focusing on sources like flaxseeds, chia seeds, and walnuts is beneficial, but supplementation with algae-based DHA and EPA is often recommended to ensure sufficient levels.

Conclusion: Finding the Right Balance

To get enough omega-3, the most straightforward approach is to consume two servings of fatty, low-mercury fish each week. This strategy ensures you receive sufficient levels of the beneficial EPA and DHA fatty acids while minimizing exposure to pollutants. Wild salmon, sardines, and mackerel are among the best options. If you don’t eat fish, strategically incorporating plant-based ALA sources and considering an algae-based supplement can help bridge the nutritional gap. The key is balance and awareness of your dietary sources to ensure your body gets the essential omega-3s it needs for optimal health. For further information on sourcing, the Monterey Bay Aquarium’s Seafood Watch program offers excellent resources for sustainable choices.

Monterey Bay Aquarium Seafood Watch: Learn about sustainable seafood choices.

Frequently Asked Questions

A standard serving is approximately 3.5 to 4 ounces (100-113 grams), which is about the size of a deck of cards or the palm of your hand.

While plant sources like flaxseeds and walnuts contain the omega-3 ALA, the body's conversion to the more beneficial EPA and DHA is highly inefficient. It's challenging to get sufficient marine omega-3s from plants alone.

Farmed fish can be a good source, but studies show that their omega-3 content has decreased over time due to changes in their feed. Wild-caught fish may have higher levels.

Larger predatory fish like shark, swordfish, and king mackerel generally have higher mercury levels and should be limited, especially by pregnant women and young children.

Supplements provide concentrated EPA and DHA but lack the other beneficial nutrients found in whole fish, such as protein, vitamins, and minerals. It's generally better to get omega-3s from food sources when possible.

If you dislike fish, alternatives include algae-based supplements for direct EPA/DHA. You can also incorporate plant-based ALA sources like chia seeds and walnuts, though their conversion to the more active forms is limited.

Most health organizations agree that 250–500 mg of combined EPA and DHA is enough for healthy adults to maintain overall health, though higher amounts may be needed for specific conditions.

The omega-3 content is generally not affected by common cooking methods like baking, grilling, or steaming. However, frying fish, especially in batter, can increase its fat content significantly.