17 Fish You Should Never Eat  

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By Jonathan Trent

Fish is a staple food in many diets worldwide, with an average of 7.1 million tons consumed per year in the USA alone. However, not every fish species is appropriate for consumption due to various environmental and health reasons, as the following 17 examples show! 


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Eels are considered a delicacy in many countries, such as the UK and Japan, but sadly, this has led to severe overfishing. Eels, specifically river eels, are also known for absorbing dangerous chemicals, which can harm the body if consumed too frequently.

Atlantic Cod 

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Cod is one of the most popular white fish to grace the human dinner plate, consumed readily globally. However, overfishing has led to a rapidly dwindling cod population in the Atlantic Ocean, which Oceana claims is nearing extinction. So, do your part for the environment and avoid eating Atlantic Cod

Atlantic Salmon

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Most variations of salmon are fine to eat, as they contain abundant protein and are an effective source of omega-3s. Atlantic salmon, on the other hand, isn’t such a healthy option. It is a farmed fish, meaning it is raised in undesirable conditions and surrounded by pesticides and parasites. Gross! 

Imported Shrimp

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Farmed shrimp imported from abroad has developed a bad reputation over the years, and rightly so. The pesticides and chemicals used in the farming process have been found to have links to an increased risk of breast cancer in women, so it should be easy to see why they’ve made this list.


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Although Tilapia is farmed specifically for human consumption and is seen as a good protein source, it is not always appealing to the palate. That’s because it is vulnerable to contamination from undesirable compounds, making it taste musty, as though it is past its sell-by date. 

Orange Roughy

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In addition to containing dangerously high mercury levels, the orange roughy has been overfished and is threatened with extinction. The species doesn’t reach sexual maturity until 20 years old, meaning it will take over 40 years for the population to become sustainable, especially if we keep eating it! 

Imported Catfish

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Catfish is a delicacy in the southern US states, where it is usually caught in nearby waters. However, catfish imported from abroad is often a subspecies known as pangasius. A study by PubMed suggests that 70-80% of pangasius samples are contaminated with Vibrio, a microorganism heavily linked with shellfish poisoning. 


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Thankfully, sharks aren’t a common menu item in the USA or much of the Western world, but they are often consumed in Asia. As sharks tend to be high up in the food chain, they contain high levels of mercury, which, if consumed in large quantities, is dangerous to humans.

Bluefin Tuna

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Bluefin tuna has been overfished almost to the point of no return, with its population having depleted by 96%. It is most commonly used in high-end sushi restaurants and exploited in the Atlantic and Pacific oceans. It might be tasty, but don’t eat bluefin tuna, or you’ll contribute to this problem.


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Swordfish is so high in mercury that women and children must stay clear of it. The negative effects of mercury particularly affect pregnant women, as high doses can dramatically affect a growing baby’s brain, putting them at risk of developing cerebral palsy and other disabilities. 


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Grouper is one of many fish species used as bait in seafood menu fraud. Due to its appeal, it is often placed on menus, only for diners to be served cheaper alternatives such as pangasius instead. So, unless you really trust the restaurant, avoid ordering the grouper.


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Wanted for their eggs and meat, sturgeon are the subject of illegal caviar trades, which have reduced the population dramatically over the years. According to the WWF, sturgeon are the most endangered species on earth, meaning you should avoid eating them at all costs. 

King Mackerel

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When ordering mackerel, always be sure to double-check which variation of the fish you are about to be served. Standard mackerel is perfectly good for you, containing omega-3s and protein. However, king mackerel is extremely high in mercury, likely harming you more than doing good.


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Aside from the reliable blue marlin caught in Hawaii, it is recommended that you avoid marlin consumption, as the fish is high in toxins. The marlin population is also in decline, not due to commercial fishing, but simply due to sport fishing, so avoid this hobby too! 


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Vendors exploit scallops as another form of seafood, often misselling them to unsuspecting diners. If the scallops on your plate are too uniform in shape and appearance, you may have been served shark, skate, or even stingray. It’s just not worth the risk of eating something unknown! 

Chilean Sea Bass

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Formerly known as the Patagonian toothfish, the Chilean sea bass was given a more commercially friendly name to appeal to buyers. Sadly, this has led to the severe overfishing of the species, with Greenpeace predicting that the fish will soon become extinct unless people stop eating it.


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Finally, unlike most other creatures on this list, octopuses are not being overfished or contain high levels of mercury. A decision not to eat them should come down to ethics, as they are highly intelligent beings. Besides, they taste very similar to squid, a more common menu item and a less intelligent species.