The Best & The Worst Fish For Your Health: General Information, Related Research

The Best & The Worst Fish For Your Health


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The below provides a general overview on this topic and may not apply to everyone. Any treatment protocol should be discussed with a qualified healthcare practitioner ... Please refer to: Medical & Legal Disclaimer.

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Potential health benefits derived from eating cold water fatty fish:

For most people, the high amounts of omega-3 polyunsaturated fatty acids and vitamin D in fatty fish provide a huge benefit to the heart and overall health. For good health, the general recommendation is at least two servings a week (optimally four or more) of cold water fatty fish (do make sure to choose fish low in contaminants -- listing below).

Please note that pregnant women, women of child-bearing years, and young children are frequently recommended to limit their intake to no more than 1 meal per month. Although most recently, some suggest that the benefits of eating fish outweigh the risk associated with contamination. Also - the level of exposure can be limited by choosing wisely the fish we eat.


  • The results of a 14-year study by "Nurses' Health" were published in the Journal of the American Medical Association in 2001. Tthis 14-year study found that eating fish at least twice a week versus less than once a month cut in half the risk of strokes caused by clots blocking an artery to the brain.
  • The above-referenced study also found that eating one to three (6-ounce) servings of fish per month cut the risk of heart disease by 20%, while eating at least five servings a week lowered risk by 40%.
  • According to a study published in JAMA, a common kidney cancer may be thwarted by eating fatty cold-water fish at a minimum once a week. The study specifically compared intake of fatty fish to lean fish, including cod and tuna, as well as other seafood, such as shrimp, lobster and crayfish, and examined the risk of Renal Cell Carcinoma (RCC) in the group of more than 61,000 Swedish women. The women were followed over a period of 15 years. Those who reported consistent long-term consumption of fatty fish had a statistically significant 74 percent lower risk of RCC. Lean fish, however, did not provide a benefit.
  • All-cause mortality rate drops by 17 percent.
  • NOTE: The same health effects may also be gained by taking supplements.
    • For example cod liver oil. Don't worry about bad taste - there are now some cod liver oils available in a pleasant lemon flavor. Click here for more info.
    • Extra virgin olive oil and flax seeds



AnchorConcerns over Mercury & Other Contaminants:

The most common contaminants found in fish include:

  • Mercury
  • PCBs
  • Toxic metals such as cadmium, lead, chromium and arsenic
  • Radioactive substances like strontium

    The highest concentrations are found in the large carnivorous fish of the ocean, such as:

Tuna / Canned Tuna

Sea bass


Oysters (Gulf of Mexico)


Largemouth Bass



White Croaker






One major concern with fish consumption is mercury (one of the most poisonous metals in existence) that is mainly found in farmed fish and fish coming from contaminated open waters. Other common contaminants in fish are PCBs, dioxins, pesticides and herbicides.

Mercury is a cumulative heavy metal poison that can damage the central nervous system and other organs or organ systems such as the liver or gastrointestinal tract. Click here for more information on mercury poisoning.

AnchorIn general, wild caught freshwater fish from the Eastern/Southern US are high in mercury, as are pelagic (open ocean free-roaming) salt water predator species (listed below), and the content is higher the older and larger the fish are. There is more Mercury in Atlantic than Pacific in general as well.


Fish Lowest & Highest in Mercury / Contaminants

  • Choose WILD Salmon over Tuna: Recent FDA tests found the average mercury level of canned albacore tuna to be at least 35 times higher than the level in canned salmon. But avoid FARMED salmon, which are crammed into pens and fed soy, poultry litter and hydrolyzed chicken feathers. As a result, farmed salmons are lower in vitamin D and higher in contaminants, including carcinogens, PCBs, brominated flame retardants, and pesticides such as dioxin and DDT.

  • Fish and shellfish have a natural tendency to concentrate mercury in their bodies. Fish that tend to have highest concentrations of mercury are:
    • Predatory fish, such as shark, swordfish, king mackerel, albacore tuna (please see below), and tilefish (Gulf of Mexico). The reason for the higher concentration is that mercury is stored in the muscle tissues of fish, and when a predatory fish eats another fish, it assumes the entire body burden of mercury in the consumed fish.
    • Health Canada states that canned tuna is safe; however, some research has found certain varieties of canned tuna such as albacore and blue fin to be higher in mercury than light or skipjack tuna. 

  • Fish with typically low concentrations of mercury include:
    • Smaller fish generally fare better than larger fish since they don’t have time to accumulate much mercury in their tissues. Good choices are shrimp, tilapia, ocean and canned salmon (avoid farmed fish, including farmed salmon), cod, halibut and catfish (FDA March 2004), as well as Atlantic herring, sardines, fresh water trout and pollock.
    • The FDA characterizes shrimp, catfish, pollock, and canned light tuna as low-mercury seafood, although recent tests have indicated that up to 6 percent of canned light tuna may contain high levels.

  • Avoid farmed fish (including shellfish) at all cost. Click here more about the impact of farmed fish on our health and the environment.

Food Remedies

  • Sports fisherman are advised to check with your local territorial authority for advisories or information on fish caught in local waters, as far as their safety for human consumption is concerned.


Other Recommendations:

  • For optimal blood sugar control, eat high-quality protein with those high-quality carbs as it slows the absorption of mercury.



AnchorAbout Farmed Fish / Shellfish

Fish farming involves raising fish commercially in tanks or enclosures. Fish species raised by fish farms include salmon, catfish, tilapia, cod, carp, trout and others.

A study published in the July 2008 issue of the Journal of the American Dietetic Association reports that the popular farm-raised fish known as tilapia and cat fish may actually harm your heart, due to the low levels of healthy omega-3 fatty acids and high levels of unhealthy omega-6 fatty acids. This combination could be particularly bad for patients with heart disease, arthritis, asthma and other diseases involving overactive inflammatory responses. There is evidence that you may harm yourself by eating farmed tilapia and catfish.

The American Dietetic Association recommends that we need to improve the way of farming fish. At the moment, fish are fed an inexpensive, inferior feed and this is having an adverse effect on the nutritional quality of the fish. Until farming techniques have improved, wild fish is recommended over farmed. Farm-raised fish are only as good as the food that we feed them, and the contaminants that the fish are exposed to in poorly maintained / dirty tanks will ultimately end up in those who eat them.


Contaminants in Farmed Fish:

Up to ten times more contaminants have been found in farmed fish when compared to wild fish. These contaminants include PCBs, dioxins, pesticides and PBDEs, which are used as fire retardants. Aquafarming also raises a number of environmental concerns, the most important of which may be its negative impact on wild salmon. It has now been established that sea lice from farms kill up to 95% of juvenile wild salmon that migrate past them.(Krkosek M, Lewis MA. Proc Natl Acad Sci U S A.)

These toxins increase people's risk of cancer and immune system and reproductive disorders. The high toxic levels caused by bringing concentrated, contaminated fish feed and adding more chemicals while farming results in farm salmon being one of the most contaminated protein sources in the world.

  • Nutrition: Farmed fish are inferior nutritrionally compared to their wild counterparts. Despite being much fattier, farmed fish provide less usable beneficial omega 3 fats than wild fish.
  • Dye: Farmed salmon are given a salmon-colored dye in their feed, without which, their flesh would be an unappetizing grey color. Wild salmon get their salmon color from their natural diet.
  • Pollution & Toxins: Farmed fish are kept in concentrations never seen in the wild (e.g. 50,000 fish in a two-acre area.) with each fish occupying less room than the average bathtub. Due to the feedlot conditions of aquafarming, farm-raised fish are treated with antibiotics and exposed to more concentrated pesticides than wild fish. This causes several forms of pollution through raw sewage, drugs and chemical contamination.
    • Administration of Antibiotics, Drugs & Pesticides: Threats include lethal sea lice infestations; parasites and viral and bacterial disease outbreaks. Because of the most common threat -- sea lice infestations - some aquaculture operators frequently use pesticides to eliminate the sea lice and strong antibiotic drugs to keep the fish alive. In some cases, these drugs have entered the environment. Additionally, the residual presence of these drugs in human food products has become controversial. The use of antibiotics facilitates the development of antibiotic-resistant bacteria, and drugs are passed to the other marine life and to humans.
    • The fish are packed tightly, rubbing against each other and the sides of their cages, damaging their fins and tails and becoming sickened with various diseases and infections.
    • Ciguatoxin-producing microorganisms have been found in farm-raised salmon. Ciguatoxin produces illness which often goes unexplained by physicians unfamiliar with a tropical toxin and its characteristic symptoms. Symptoms of ciguatera include gastrointestinal symptoms, such as include nausea, vomiting, and diarrhea, usually followed by neurological symptoms such as headaches, muscle aches, paresthesia, numbness, ataxia, and hallucinations. Severe cases of ciguatera can also result in cold allodynia, which is a burning sensation on contact with cold (commonly incorrectly referred to as reversal of hot/cold temperature sensation). Ciguatera poisoning is frequently misdiagnosed as multiple sclerosis.
  • Ecological Impacts.
    • Pollution: Fish farms are producing waste equivalent to the sewage of a city of 100,000. There is a very real risk of disease transfer from farmed salmon to the wild stocks. Norway provides a devastating example, where almost 30 river systems have had to be deliberately poisoned in order to stop farm-bred disease. The costs of the loss of ecosystem and regeneration are impossible to measure and will be borne for generations. The direct effect on other marine species is still in question.
      • The very large number of fish kept long-term in a single location produces a significant amount of condensed feces, often contaminated with drugs, which affect local waterways. Open-net-cage salmon farms dump raw sewage directly into the sea and onto the sea floor. The amount of sewage that B.C. salmon farms spew on the delicate marine life is equivalent to a city of 100,000.
      • This untreated waste is laced with antibiotics, pesticides and other chemicals. These toxins contaminate sea life in and around the farms, cause toxic algae blooms and deplete the oxygen in the water that then asphyxiates marine life.
      • The nets used to contain the fish are treated with chemicals so toxic that when the nets are cleaned, the resulting sludge is shipped to a toxic waste site. What is the cost of the environmental effect of these nets hanging in the ocean, as well as the buildup of land-based toxic waste sites?
    • Infestations: Wild salmon populations have been devastated by sea lice parasite infestations originating from salmon farms. Another groundbreaking scientific study was published in the peer-reviewed journal Proceedings of the National Academy of Sciences that confirms that sea lice from salmon farms in the Broughton Archipelago killed up to 95 percent of wild salmon during the springtime migration.
    • The world's fish stocks are being depleted to raise farm salmon. It takes two to eight kilograms of wild fish to raise one kilogram of farmed salmon. This causes a global net loss of protein. Most of the fish, like anchovies, that are used to make feed come from off the coast of Peru and Chile. So fish that could be otherwise eaten by people in developing countries, and which is often the main source of protein for them, is instead being overfished and used to raise a luxury product.

  • Many salmon farms are adding artificial color to make the salmon flesh appear more pink or red because that's what consumers will buy. Imitation crab meat has artificial colors added to make part of the meat look red.


Shellfish Operations:

Ecological Impact: High densities of shellfish operations are associated with a decrease in species richness, altered species abundance and distribution, change in community intertidal structure to one composed primarily of bivalves and greater accumulations of surface sediment, silt and organic matter. A steep decline in starfish, crabs and some species of jellyfish, as well as a marked decrease in the diversity of marine and non-marine species; and unprecedented deterioration of summer water quality has been observed.

Farmed shellfish is frequently contaminated with cadmium. Cadmium, and its compounds, are extremely toxic even in low concentrations, and will bioaccumulate in organisms and ecosystems. Ingestion of any significant amount of cadmium causes immediate poisoning and damage to the liver and the kidneys. Compounds containing cadmium are also carcinogenic. The bones become soft (osteomalacia), lose bone mass and become weaker (osteoporosis).

(Source: Minutes from the Meeting by the SPECIAL COMMITTEE ON SUSTAINABLE AQUACULTURE, Tuesday, October 17, 2006
12 noon
 - Province of British Columbia - 38th Parliament – 2005-06
Special Committee on Sustainable Aquaculture


Information contained on this website is provided as general reference only. For application to specific circumstances, professional advice should be sought.


GreenAndHealthy.Info strives to maintain accurate and up-to-date information; however, mistakes do happen. If you would like to correct or update any of the information, please send us an e-mail. THANK YOU!

Information contained on this website is provided as general reference only. For application to specific circumstances, professional advice should be sought.

GreenAndHealthy.Info strives to maintain accurate and up-to-date information; however, mistakes do happen. If you would like to correct or update any of the information, please send us an e-mail. THANK YOU!