How to Eat Fish, Rich in Omega-3 Fats, without Mercury and without Going Broke.

I was recently asked by a magazine editor to clarify how to find Omega-3 rich fish, without mercury and at a reasonable price. The best way I have found  is to look at three key characteristics of these fish:

  • they live in cold water
  • have small mouths
  • and have short life spans

Highly beneficial long chain omega-3 fats are found in algae that live in cold water; the advantage for the plants is that these fats don’t turn stiff in this cold environment. Algae that contains Omega-3 fats are eaten by progressively bigger shrimp (krill) and omega-3 content increases as it moves up through the food chain and accumulates in high quantities in fish, with bigger fish usually having more omega-3 fat as they are higher in the food chain. In contrast, warm water fish have very little omega-3 fats because they do not have access to omega-3 rich algae. Examples of fish that are rich in omega-3 fat are: anchovies, sardines, herring, wild salmon, white fish, and fresh water trout.

In humans, long chain omega-3 fats enhance brain performance, decrease the risk for sudden cardiac death, lower inflammation, improve blood sugar control, improve cholesterol profiles, decrease arthritis joint pain—the benefits go on and on. The downside is these fats are very delicate, and poor quality omega-3 products may turn rancid and “likely” cause as much harm as benefit, as an increased risk of cancer. Fish from polluted waters also contain many harmful contaminants. Thus, the quality of the source for omega-3 fats from fish or fish oil supplements, is of high importance.

Please don’t confuse middle-chain omega-3 fats from soy, flax, etc with fish sources. The plant-based middle-chain omega-3 fats, frequently advertised as sources of omega-3s,  have none of the proven beneficial properties of long-chain omega-3 sources (from fish). This is a critical distinction, as many companies falsely market their plant-based omega-3 products as containing healthy omega-3 fats. As an example, ground flax seed is a healthy food product, but not because of its omega-3 fats.

Fish with small mouths eat lower on the food chain, hence they accumulate less heavy metals in their tissues. Wild salmon, with a small mouth that eats small shrimp has nearly undetectable mercury levels, while a similar sized tuna or grouper that eats bigger fish can be very high in mercury. Mercury is one of the most important contaminants in fish. I test mercury on all my patients, and nearly 30% of my Florida patients have high mercury levels. The irony is people are eating more fish for their health, but too often are damaging their brains in the process. Mercury is a neurotoxic metal and can cause burning and tingling in nerves, ringing in the ears, and cognitive decline. We published a study last year (Masley SC, Masley LV, Gualtieri T. Effect of Mercury Levels & Seafood Intake on Cognitive Function in Middle-aged Adults. Integrative Medicine 2012;11:32-40) showing that people with mercury level above 15 (11 is the top of normal with most labs) had decreased brain speed, which is strongly associated with permanent memory loss and greater Alzheimer’s risk. While those who ate more omega-3 rich fish and had normal mercury levels, had better cognitive function.

The lifespan of a fish is less important than mouth size, yet it plays a role. If a fish lives to be 20 years old (a halibut), it will accumulate much higher mercury levels than a wild salmon that has a 2-4 year lifespan. So fish with fairly short lifespans (salmon, herring, sardines) are better choices. If you can catch halibut that are under 20 pounds, they are younger and have smaller mouths as well (double benefit), but it is very hard to know the weight or lifespan of a fish when you order it in a restaurant.

Regarding cost, fresh wild salmon is very expensive. Vacuum-packed frozen wild salmon (such as coho/silver) is a good choice, at half the price. With frozen salmon, I usually rinse and then marinate vacuum-packed salmon in orange juice for 10 minutes before seasoning and cooking, which really helps the flavor and protects the flesh when grilling.

The best value is canned wild salmon (typically a 6-7 ounce can is $6 for sockeye (red), and $4 for pink salmon (pink salmon has a flavor closer to tuna). You can buy a 12-pack of 3.5-ounce canned sardines packed in olive oil or tomato sauce for $2.50/can, so actually these are about the same price. Do not buy the sardines packed in cottonseed oil (or other bad oils) as you lose the health benefits with this choice. Many people don’t like sardines, so for the general public, canned wild salmon is the least expensive, most realistic way for people to get their omega-3 fix.


Canned, wild salmon is a much better health choice than tuna, which is high in mercury. Try my Salmon Spread recipe adapted from my upcoming book: The 30-Day Heart Tune-Up. People who like tuna salad will enjoy this recipe, and may save them from the disabling effects of mercury toxicity.


PREPARATION TIME: 5-10 minutes


6 ounce           Canned salmon (I prefer wild Alaska pink or red salmon, no bones or skin)

2 medium       Green onions, diced

1 Tbsp             Dijon mustard

2 Tbsp             Hummus (or organic canola mayo)

1 Tbsp             Capers

1 tsp                Lemon juice

1 medium       Celery stalk, diced

Optional         Hot sauce to taste

Drain  salmon and mix with the remaining ingredients. Serve over lettuce, as sandwich spread, or with veggie sticks as an appetizer.

Lastly, farmed-raised salmon is swamped in controversy. If it is raised in pristine waters and given a healthy food source, such as herring or sardines, it is an excellent choice. If it is raised in polluted water and fed ground up by-catch and contaminated feed, it would be a terrible choice. People buying farmed raised fish should research where it was raised and how it was produced.


Below are tables (adapted from information in Heart Tune-Up) that balance recommendations for fish that are high in long chain omega-3 fats and low in mercury.  

BEST CATCH The following are high in Omega-3’s, fairly low in saturated fat, and low in mercury. Enjoy up to 3-5 servings per week. All are based on a 3.5-ounce serving, unless noted.



Herring,   Atlantic






Salmon,   Atlantic, Wild


Salmon,   Coho (Silver), Pacific, Wild


Sardines   (water packed, no oil added)




Trout,   Rainbow, Wild


Trout,   Rainbow, Farmed


White   Fish




GOOD CHOICES The following are low in mercury, but also low in omega-3 fats. They aren’t as good as salmon or sole, but better protein sources than chicken or turkey breast choices. Enjoy up to 2-3 servings per week.




Calamari   (squid)


Catfish,   Channel, Farmed




Cod,   Atlantic


Crab,   Dungeness (fresh)


Halibut   (small halibut, <20 pounds, are better)


Lobster,   Spiny (or salt water Shrimp)


Mahi   Mahi (Dolphin fish)




Scallops   (6 ounces, raw)




  LIMIT YOUR INTAKE ON THESE FISH The following are moderately high in mercury (more than 0.2 parts per million), so limit to not more than 2-3 servings monthly. In general, large mouth fish are higher in mercury levels. Skipjack (light) tuna is the lowest in mercury.




Bass   (including Chilean Sea Bass)






Lobster,   Maine


Tuna,   Albacore


Tuna,   Bluefin


Tuna,   Yellowfin


              THROW IT BACK! The following are high in mercury (greater than 0.5 parts per million). Avoid these fish as much as possible. King Mackerel






  1. Teresa Wilson says:

    Just wondering if you consider canned kippers (kippered herring) a good choice? I haven’t had them in years, but I used to love them when I was in college.

  2. Great recipe Dr. Masley. I canned a lot of coho salmon this year and would like to share a similar salmon spread.

    6 oz canned salmon
    2 Tbs organic Greek yogurt (plain)
    1 Tbs organic canola oil mayo
    2 green onions chopped
    1/2 apple chopped
    1 celery stock chopped
    Add some black pepper to spice it up if you wish. This is excellent served on a bed or greens.

Speak Your Mind