There are many fish in the sea but that doesn’t mean they’re all good for you. So is fish bad for you and are there certain types of fish that you should avoid…
Eating fish has been recommended by the American Heart Association as part of a healthy diet to fight heart disease (1). Fish is naturally high in healthy omega-3s that have been found to lower the risk of heart disease. If you have high blood pressure then the omega-3s in fish and seafood can lower your levels (2).
But there are certain fish species that can contain high levels of mercury which can bring you more harm than health. Mercury can lead to serious health problems and can even contribute to obesity and malfunctioning metabolism (3). You also might want to avoid fish that come from fish farms.
Pregnant women or those breastfeeding should limit their consumption of fish to 8-12 oz. per week according to the FDA. And women who are pregnant should pick fish species that contain low levels of mercury.
Now there are fish that are good for weight loss but there are some fish species you should really avoid. Not only because of high mercury levels but because they just aren’t healthy for you.
Pros and Cons of Eating Fish
The fish you’ll find on my list of the best for weight loss are fantastic for helping you lose weight, prevent cardiovascular diseases, and even improve cognitive strength.
Eating fish can bring you many health benefits like weight loss and improved heart and brain health (4). Fish is high in protein, contains healthy omega-3 fatty acids and other vitamins like vitamin B12 that are also really good for your health (5).
But it’s not a great idea to eat fish every day because of the mercury content. The mercury in fish is by far one of the biggest dangers of eating fish. The FDA recommends 8 ounces of seafood per week based on a 2,000 calorie diet.
Eating fish can also be bad for the environment depending on the species and if fish caught in the wild or if it was farmed. Seafood sustainability is important to ensure oceans are able to maintain their ecosystem balance for generations to come (6).
And there are bad fish out in the sea you should avoid and I’m not just talking about the shark in Jaws. These fish while having some benefits will have cons that far outweigh anything positive you could get from them.
So if you’re on an all-canned tuna diet then it’ll be a good idea to start cutting back before your mercury levels go through the roof.
It’s best to stay away from these fish to not only lose weight but to avoid any serious health problems.
Farmed Atlantic Salmon
Farmed Atlantic Salmon is one of my most hated fish that I unaffectionately call the “Evil Twin.” It’s really unfortunate most people unknowingly pick up this bad salmon in the grocery store are putting themselves at risk for some serious health problems.
Now farmed salmon will be a lot cheaper than salmon that’s wild caught but the latter will be worth the extra price. Farmed fish contains higher levels of saturated and polyunsaturated fats compared to wild caught salmon (7). Farmed salmon also contains almost 50% more calories because of these fats.
Farmed Atlantic Salmon are fed a soy-based diet and they’re found to be high in toxic Polychlorinated Biphenyls (PCBs) (8). These PCBs are really bad for your health and can even lead to cancer (9). They’re a hormone disruptor that can negatively impact your metabolism by altering your testosterone and estrogen levels (10).
Many farm-raised salmon is dyed pink to make it look like they have the same bountiful omega-3s as their “Good Twin” Alaskan Wild-Caught Salmon (11).
Now farmed contains about the same amount of omega-3s as wild caught. But the problem is farmed salmon contains almost six times the amount of omega-6 fats. Eating too many omega-6s can lead to inflammation in your body as well as heart disease and weight gain (12).
This is why it’s a smart idea to supplement with an omega-3 like the one you can find in my OmegaKrill review. It’ll help to rebalance your omega-3 to the omega-6 ratio which will reduce inflammation in your body.
While having only 1/4 the vitamin D as Alaskan Wild-Caught Salmon farmed salmon are crammed into pens where diseases and parasites can flourish. This requires the farmers to use antibiotics and pesticides on the farm-raised salmon that make their way onto your plate.
Disturbingly enough, the FDA in November 2015 approved genetically engineering salmon while not requiring any labeling for consumers. And this study found farmed salmon to actually cause weight gain in mice (13). The mice also showed signs of metabolic syndrome and type 2 diabetes.
So if I were you I’d really try to avoid farmed salmon at all costs.
Atlantic Bluefin Tuna
The New York Times found Atlantic Bluefin Tuna to have the highest amounts of mercury than any other tuna (14). Mercury is not only toxic for you but it can also cause weight gain by disturbing your thyroid gland and pancreas. Both of which are extremely vital to regulating your hormones.
The International Union for Conversation of Nature has deemed Atlantic Bluefin Tuna to be extremely over-harvested and at risk for near extinction.
It’s much easier and better for your belly to eat canned light tuna instead of going with this mercury-laced fish. Even albacore tuna contains a higher amount of mercury which is why picking out a light canned tuna or canned sardines will be a better seafood option.
This might be a shock to you as most restaurants and quick food eateries use tilapia for their fish. Tilapia is the iceberg lettuce of the fishes.
They’re low in omega-3’s and higher in belly fat causing omega-6 fatty acids. While omega-3’s have been found to lower abdominal fat, omega-6 fatty acids have been associated with an increase in stomach fat (15).
Also, be aware most tilapia is farm-raised and fed a corn-based diet when they should be out in the wild eating lake plants and algae.
If you’re going to eat swordfish then you might as well just start drinking a big glass of mercury right now.
Swordfish is notorious for being super high in mercury. Mercury is a well-known endocrine disruptor that can wreak havoc on your thyroid and pancreas.
This will cause your hormones to get out of whack and make you start to store more fat along with a plethora of other health problems.
The mercury in swordfish tricks your body into storing more fat, burning fewer calories, and even reduces the appetite-regulating hormone leptin (16).
Even though swordfish does have a good amount of selenium and vitamin D the risks really do outweigh any benefits you’ll get from eating it. Marlin and Sailfish are two closely related fishes that should also stay off the menu as these fish also tend to contain higher mercury levels.
This might be a no-brainer but I thought I’d include fish sticks on my list of the worst fish for weight loss.
Fish sticks are breaded and fried, which usually also means they have trans fats in them. Don’t forget they’re also high in calories and sodium.
Just one fish stick contains 78 calories. In fact, I’d even go so far as to recommend eating chicken nuggets as the lesser evil here.
If you have a love for fish sticks and won’t give them up then be sure to search for fish sticks that are reduced fat and baked instead of fried.
Eel / Unagi
Eel is a popular choice for sushi you can find at virtually every sushi restaurant on the planet. I’ve eaten at many sushi places in my day and for the longest time thought eel was good for me.
With the rise in popularity in eating eel sushi, their numbers have been greatly depleted. Eel is rarely farmed and usually caught out in the wild. Their mercury levels are generally on the lower end and generally safe in that regard.
But it’s best to stay away from eel as best you can. Eel are bottom feeders so they’re basically chewing up everything that’s rotten and died that fell to the water floor. So they could be consuming higher mercury fish that will then transfer into their bodies too.
Luckily, it’s not a popular choice for fish but it can be dangerous if you like to eat sushi a lot.
Sharks are at the very top of the food chain, and this means they’re extremely high in mercury. They’re also very low in protein and omega-3 fatty acids.
Sharks are just not a smart choice for healthy fish that will help you lose weight. Additionally, shark consumption can cause the ocean ecosystems to suffer since they’re at the top of the food chain.
Without them, rays and jellyfish become over-populated leading to the rest of the ecosystems suffering.
There isn’t much to say about Tilefish other than you should skip them at all costs. Their levels of mercury is so high that the general medical advice is to not eat them.
Tilefish caught in the Gulf of Mexico tested highest for mercury for all fish by the FDA. Tilefish from the Atlantic Ocean contains less mercury but still should be limited consumption.
The Environmental Defense Fund (EDF) recommends women and children to not eat any Tilefish whether it’s from the Gulf of Mexico or the Atlantic (17). It’s best just to stay away from this seafood.
King Mackerel contains such a dangerous amount of mercury that even health officials warn against eating it. Mercury builds up in your body and before you know it causing damage.
If you just love King Mackerel then make sure you eat one that’s less than 33 inches and limit your consumption.
Pregnant women should avoid it completely as the mercury could cause neurological damage to their unborn baby.
Shrimp normally would be on the approved fish list for weight loss, but considering 90% of shrimp in the U.S. is imported there are things you need to know about.
Shrimp are not only lacking in the nutrition department but imported ones are high in contaminants. There isn’t much regulation for shrimp in foreign countries and you can expect to find chemical residues, antibiotics, and even traces of E. coli.
Shrimp is fine when you buy it domestically and even has a good amount of iodine that can be good for your thyroid.
Just be sure to search out for domestic shrimps instead of the gross imported ones.
Catfish are bottom feeders that don’t deserve a spot on your dinner plate.
They’re exposed to toxins such as man-made PCBs that have been found to cause cognitive deficiencies in infants and also affect your hormonal metabolism.
Unfortunately, 90% of the imported catfish comes from Vietnam where they also use antibiotics. The Federal Government doesn’t consider this imported catfish from Vietnam (Swai and Basa) to technically even be catfish so they’re not held to the same inspection rules.
Best to keep these nasty bottom-feeders out of your body.
Orange Roughy is a deep-sea fish that contains high levels of mercury. This fish can live to be over 100 years old which makes it very easy to build up high levels of mercury.
Plus Orange Roughy is extremely susceptible to overfishing since it takes so long for their species to mature. It’s best to avoid this species of fish not only to avoid its high mercury levels but also for the sustainability of its species.
The Last Word
Eating more fish and seafood is generally recommended medical advice. The healthy omega-3 fats found in fish has many benefits including brain health and heart health.
But there are still some fish on the list that you should avoid. Mostly because of their high mercury levels. This is why it’s not a good idea to eat fish every day. It’s also a good idea to eat a variety of good fish instead of just one species.
If you’re thinking about becoming pregnant, are pregnant, or breastfeeding then it’s a good idea to talk to your doctor first before eating a lot of seafood. Be sure to follow the FDA’s guidelines on fish consumption and to eat lower mercury fish.
Fish tend to have many benefits like high protein and omega-3 fats but there are still some bad fishes you’re going to want to stay away from.
Josh holds a Bachelor’s degree in Exercise Physiology and Nutrition Science. He’s a Certified Strength and Conditioning Specialist (CSCS) by the National Strength and Conditioning Association. He’s worked as a Strength and Conditioning Coach at the high school and college level. He has over 10 years experience as a personal trainer and nutrition coach. He is also the author of The Flat Belly Formula. He hopes to be able to bring inspiration & results to people all over the world to live a healthier life through diet & exercise.