Farmed Fish: What You Need to Know (& Why You Need to Avoid Them!)

Farmed Fish

It’s true, fish are wonderfully nutritious – but it’s important to be wary of farmed fish. They are bursting with omega-3, Vitamin B6, Vitamin B12, magnesium, phosphorous, and protein. They are low in sodium, too. However, there’s a massive difference between wild fish and farmed fish. Whether you’re talking about salmon, cod,  sea bass, shrimp, or mussels, farmed fish have far less natural nutritional value than their wild brethren. They also carry more disease and parasites, and their flesh contains far more toxins. Yet an awful lot of people are totally unaware of the danger and fail to check for the “wild” label.

While it’s true that wild fish is often a little more expensive than the farmed variety, what price can you truly put on your health and the health of the ocean?

Environmental Risks

Prepared salmon

Farmed fish live in confined, often cramped conditions, which creates an imbalance in the local eco system and encourages disease and an increase in the instances and severity of parasitic infection.


When large volumes of fish are farmed in a comparatively small area to maximize yield, they produce vast amounts of excrement. This settles beneath the nets or pens in which the fish are contained, as does all the food he fish don’t eat fast enough. These waste products create a breeding ground for harmful bacteria which poisons not only the fish in the nets, but wild marine life, too, unbalancing the ecosystem and introducing harmful diseases.

Overcrowded fish farm
Image source:

Ill Health

Ill health applies to both the farmed fish and the wild fish that they contaminate. With huge numbers of fish kept in such close quarters, the risk of disease is high. It spreads like wildfire. As do parasites like sea lice. Now yes, fish farmers can treat their captive creatures to cure them of these diseases and infestations, but the bacteria and parasites spread quickly into the wild population. Non-native species can even bring new bacteria and disease that the native populations have absolutely no dense against, which can decimate the wild populations. 

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This diseased rainbow trout is one of 1.5 million fish that escaped after a severe storm in Norway in January 2015. Image from
This diseased rainbow trout is one of 1.5 million fish that escaped after a severe storm in Norway in January 2015. Image from

Pressure on Wild Fisheries and Wild Populations

In part, this goes back to the prevalence of disease and parasitic infestation introduced to the wild from farmed stocks. For example, sea lice from farmed salmon can kill up to 90 percent of vulnerable juvenile wild salmon each year. This is a startling figure, and juvenile wild salmon have no defense against the parasites. This is just one of many ways that farmed fish damage and deplete wild stocks.

Juvenile salmon with sea lice
Photo: Alexandra Morton

Bait fish that carnivorous farmed fish, like salmon, feed on, such as anchovies, mackerel, and sardines, are dangerously over-fished to supplement the diet of farmed stock. So, instead of aiding in the sustainability of wild stock, farmed fish actually contribute to the depletion of wild fish populations. Overfishing of these food stocks also reduces the numbers of larger wild fish, like wild salmon, that rely on these fish as their main food supply.


Nets get holes – and unless someone notices immediately – the farmed stock can make good their escape. Huge numbers of farm fish escape every year, with around 1,000,000 salmon escaping per year from the Puget Sound area alone, according to These alien species compete with the native ones and are a serious threat to biodiversity. An increasingly common practice is to feed farmed fish drugs and growth hormones that means they grow around six times faster than wild species, so large numbers of these fast-growing fish quickly out-compete wild populations and consume larger quantities of food, seriously threatening biodiversity and wild fish populations.

Environmental dangers of aquaculture
Image courtesy of Dr. George Pararas-Carayannis

Health Risks of Farmed Fish

Now, aside from the threat to our marine life, farmed fish are risky for us, too. There’s a whole bunch of chemicals in farmed fish that you don’t find in the wild populations and that are potentially very bad for us.

health risks of farmed salmon
Here’s just some of the nasties lurking in farmed fish.
Image from


Dr. Anne-Lise Birch Monsen of the University of Bergen, Norway, describes how toxic substances are absorbed by fish stock, both wild and farmed. These contaminated fish are then used to create farmed fish food, but even after processing, the chemicals remain in the fish meal and contaminate the fish the meal is fed to. After processing, these toxins bind to fat cells in the bodies of farmed fish and, when you consume said fish, the toxins contaminate you, too, binding to your cells and interfering with a variety of essential body systems. While these are dangerous to all of us, the toxins found in farmed fish are particularly dangerous to pregnant women, nursing mothers, and infants.

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The type of contaminants that have been detected in farmed salmon have a negative effect on brain development and is associated with autism, ADD / ADHD and reduced IQ. We also know that they can affect other organ systems in the body’s immune system and metabolism.Dr Monsen, of the University of Bergen, Norway


Dioxins are some of the most dangerous toxins found in farmed fish. According to the World Health Organization, these chemicals have a variety of dangerous effects:

  • Carcinogenic
  • Alters liver function
  • Damages the immune system – and has the potential to cause auto-immune diseases
  • Can induce skin sensitivity
  • Causes fertility and reproductive problems
  • Impacts the endocrine system
  • Causes multiple developmental effects
  • Highly dangerous to developing fetuses and newborns

Although the use of dioxins is heavily restricted in some countries, they still find their way into the food chain, and the presence of these chemicals is around 11 times higher in farmed fish than in wild ones, according to a study by David Carpenter of the University at Albany, N.Y. This alone is a good enough reason to never touch farmed fish again.


Everyone and every creature is prone to the occasional infection, and it’s common practice to use antibiotics to combat this. However, the conditions in which farmed fish are kept opens them to an increased risk of infection, due to cramped living conditions, undue stress, and improper feeding. So, the use of antibiotics is significantly greater. Additionally, many fish farms use antibiotics regularly as a preventative or prophylactic measure. This means:

  • You can consume these antibiotics when you eat the fish
  • Bacteria that cause infections adapt and become resistant to the medications – and not just marine bacteria – but microbes that cause human and animal infections, too.


Salmon is pink, right? Wrong. Wild salmon is naturally pink, thanks to the vast quantities of krill they consume. Farmed salmon, because they are largely fed a drug-laced manufactured food, are a grey-ish color. Which isn’t particularly appetizing. And, because everyone knows that many consumers shop with their eyes, since the 1980s, farmed salmon has had a host of different chemicals added to mimic the natural, distinctive pink of wild salmon. Thankfully, some countries, including the US and the UK, require producers to inform consumers via the label, if the salmon has added color. Unfortunately, lots of people don’t think to look – instead they see bright pink salmon fillets at a good price, and snap them up, not realizing they are filling themselves with chemicals. Pure Salmon state that Canthaxanthin is one of the most common salmon colorants, yet it is known to cause eye problems and retinal defects and damage in humans.

Nutritional Differences

Because farmed fish are fed a manufactured meal instead of their natural diet, their nutritional value is greatly reduced, leading some to refer to farmed fish as “swimming corncobs”. These mass-produced fish have more fat and less of the good stuff.

Fish type – 100 gramsFat per 100 gram servingOf which fat is Omega-3 (%)Calories per 100-gram serving
Wild Atlantic Salmon6.3427142
Farmed Atlantic Salmon10.8517183
Wild Coho Salmon5.9322146
Farmed Coho Salmon7.6716160
Wild Trout3.4620119
Farmed Trout5.4017138
Wild Catfish2.821995
Farmed Catfish7.595135


The table lays out the basic nutritional differences, according to the USDA, clearly – but remember there’s also a similar difference in niacin, magnesium, vitamins, and other trace minerals.

What Can You Do?

Be an informed consumer. Pay attention to what you’re buying. Always check the label. Make sure you purchase “wild” or, even better, “wild, line-caught”. Avoid anything that mentions “farmed” and don’t buy “dyed” or “color-added” fish. Use your brain – for fish like salmon, if it’s out of season, it’s not wild. And yes, you will likely pay a little more for it, but even though your wallet will be a little lighter, you’ll be doing yourself and your loved ones a huge favor, easily reducing the amount of chemicals and toxins you expose them to. And you can always buy the healthier, safer, wild fish varieties in bulk when you see them on offer, then prep them and stick them in your freezer for use throughout the year.

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1 thought on “Farmed Fish: What You Need to Know (& Why You Need to Avoid Them!)”

  1. Eating fish isn’t so healthy after all. Too bad that I don’t have any access to wild salmon (my favorite fish) here in my area. Perhaps I should stop consuming salmon at the moment?


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