Fish: What Kind Is Best?
With all the choices, it's hard to know what's good, here's a guide
TLDR: Scroll down for a list of fish we eat and ones we avoid. Plus, BPAs in canned fish and info on salmon poisoning disease in dogs.
While we love fish, we also avoid many kinds of fish. With so many different pollutants in the world now, it’s difficult to know what’s safe. People we know have gotten mercury poisoning from eating too much seafood. Several celebrities have also detailed their experience with mercury poisoning.
On top of mercury, there is industrial waste in the fresh water system in the U.S. and most countries. Chemicals like PCBs and PFAS are found in almost every lake in America. PCBs are linked with cancer and hormone issues as are PFAS, the “forever” chemicals. PFAS make up durable goods like Teflon, so these chemicals are resistant to breakdown. Furthermore, PCBs were banned in the 70s but still found everywhere in our water.
Because of all the issues, many people just avoid seafood, but we think this is mistake.
If you’re a regular reader you probably already know that we prefer small fish like anchovies and sardines, but you probably don’t know exactly why. This post shares our perspective and the research behind it. We also include a list of fish that we eat and those we avoid. By sharing how we make our choices, we hope to raise questions that might help our readers to make better decisions when buying fish.
Before that here are this week’s recipes:
So many choices
There are a so many options when you buy fish. First you have to choose which kind of fish. Then you may have to select from canned, fresh or frozen. If you get fresh fish you’ll have to choose from farm raised and wild caught or maybe previously frozen. But there’s actually something that’s even more important.
We avoid fresh water fish
There are still some pristine fresh water sources in the U.S. Remote lakes and rivers fed by snow packed mountains represent some of the finest water in the world. Yet, the vast majority of fresh water is increasingly contaminated. Run-off from agriculture, highways, industry and sewage seep into the environment and subsequently the fresh water supply.
According to the EPA, 51% of the freshwater fish sampled in U.S. lakes exceeded the organizations guidelines for mercury levels of 0.3 ppm. For context wild caught salmon has 0.03-0.05 ppm mercury or about 1/10 of the content in most lake fish. PFAS, the “forever” chemicals mentioned above, were detectible in 95% of samples, while 23% of samples exceeded the cancer screening level of PBCs for high-frequency consumers.
In addition to toxins, freshwater fish have more parasites that are able to infect people (see salmon poisoning below). This happens for several reasons.
The high salinity in saltwater requires special adaptations for parasites, making it harder for them to survive in people.
Freshwater is a milder and more ideal environment for parasites.
Freshwater is used for drinking and bathing by humans and other terrestrial animals, leading to more contact and adaptation for parasites to live inside of us.
You choose where your fish live and what they eat, kind of…
These days when you buy chicken eggs you can decide which accommodations and food are given to chickens that laid your eggs. If you want to eat eggs from chickens that live in a pasture and eat soy-free foods, you can. If you don’t mind eggs from chickens that live in a cage and eat cheap food you’re free to buy those as well. Research has shown that these factors can influence egg quality and micronutrient content.
See this post about chicken and eggs.
The same is true of fish. But because of the huge differences in water quality and marine biology, the affects to toxins in fish can be amplified.
Wild-caught fish eat a natural diet of the freshest food they can find. They are swimming in their natural waters and are less stressed than their farmed counterparts.
Ocean farmed fish are usually raised in large pens in the open ocean. These pens are very crowded, but because they are in the ocean, their water quality is less of a concern. However, their cramped conditions lead to increased stress and communicable diseases. Farmers often use antibiotics and other chemicals to control infections and reduce loss. These substances can build up in the tissue of farmed fish.
The feed used in aquaculture can drastically affect the quality of the fish. Farmed fish are often fed seafood byproducts which can introduce more toxins like mercury and PCBs, in addition to terrestrial toxins from molds and bacteria. Because the marine food chain is so vast, toxins get very concentrated at the top of the food chain. (The ocean has 7 trophic layers, where terrestrial food chains have 4 or less, see link above.)
Farmed freshwater fish is the worst choice
Since fish are farmed using water diverted from lakes, rivers and ground water, the conditions for farmed fresh water fish are usually worse. Freshwater aquaculture is generally done in ponds filled with this diverted water. Most aquaculture systems change the water infrequently, while others rarely change their water, leading to more contamination as the fish release their waste. This is especially true of fresh water farmed fish imported from emerging nations.
Examples of farmed freshwater fish include lake trout, tilapia, catfish, swai, carp, large mouth bass and barramundi.
While there are intensive farming practices that change water daily, these are still rare, and the water quality is limited to their source. Since most lakes and rivers have pollutants, so too do most farmed fish. It’s also currently difficult to trace aquaculture practices. Certification bodies have good intentions, but they are businesses and have little incentive to police their customers. We expect all of this to change in the future, but for now, we avoid fresh water farmed fish.
We prefer ocean fish
Because the ocean is all connected it can be seen as one big water system. Being so massive, any pollutants are spread out over a huge body of water, so the fish that comes out of the open ocean are generally safer. Wild caught salmon tends to be low in mercury and other toxins. Very small fish, who feed on the smallest animals in the sea, also have lower levels of pollutants.
Ocean fish we eat regularly (2-3 times per week or more):
Wild caught salmon
Anchovies
Sardines
Atlantic mackerel
Ocean fish we eat occasionally (a few times per month):
Rock fish
Snapper
Mahi mahi
Farmed salmon
Cod
Halibut (Caught in remote areas like Alaska)
Sablefish (black cod)
Tuna (smaller tuna like skipjack is lower in mercury, while larger tuna like Ahi or bluefin is a very rare treat)
Ocean fish we avoid:
Swordfish
Shark
Marlin
Orange roughy
Chilean seabass (patagonian toothfish)
Not all ocean fish is safe. Specifically predatory fish or those that live in areas where waste water runoff enters the sea. Fish like red drum, striped bass and sea trout tend to live in estuaries where rivers and streams meet the ocean. These areas are often vulnerable to pollutants from local activity.
Also fish that live in polluted bays and sounds, where city waste enters the water, are more likely to feed on contaminated animals. Sounds and bays are partially enclosed and exchange water with the ocean at a slower rate than open water. Sediment also accumulates pollutants. Bottom dwellers like halibut, are more likely to be exposed to toxins that accumulate on the sea floor, like heavy metals and PCBs.
Although they live in the open ocean, predatory fish like swordfish, shark and large tuna have high very high levels of mercury. They eat large fish that already have higher amounts of environmental pollutants from their food. This phenomenon is known as biomagnification, older and larger predatory fish accumulate mercury at up to 100-times the concentration of small fish.
Canned fish
The chemicals BPA and similar compounds are linked with hormone disruption in people. Because cans are lined with plastic, numerous studies have shown concerning levels (up to 1000% increase) of BPA in people after consuming canned soup.
Many cans are now BPA-free, but some of the alternatives used are also potentially harmful. So when choosing canned fish, we typically opt for higher priced products labeled BPA-free. Also, we tend to only feed canned seafood once per week.
Salmon Poisoning Disease in dogs
Can dogs eat raw fish? Technically, yes, but the type of fish, source of the fish and how it’s processed matter.
There have been cases of dogs falling ill after eating raw salmon and trout in the United States. Why does this happen?
Nanophyetes salmincola is a flatworm that is endemic to the west coast of the US. This flatworm harbors a bacterium that can cause infections in dogs. Symptoms are similar to distemper and include vomiting, diarrhea, fever and lethargy. Most dogs treated quickly make a full recovery. However, left untreated, salmon poisoning has up to a 90% fatality rate.
Sashimi grade salmon from reputable sources is typically free from this pathogen. Salmon used for sashimi is usually farmed and treated for parasites, unlike wild salmon. If you live in Washington, Oregon or California, wild caught salmon and particularly those fish caught in fresh water, have a high likelihood of containing the parasite. Fully cooking wild-caught salmon will eliminate the risk of your dog contracting the disease.
Conclusion
Despite the risks of eating fish and seafood, we believe that with careful selection, the benefits are far greater. By limiting choices to the safest fish, your family and your pups can reduce consumption of pollutants while getting all the wonderful benefits.
That’s all for this week.
All the best,
Joelle and The Precious Creatures Team