Salmon, tuna, and cod are the fish of choice for many health-conscious eaters. Though delicious and nutritious, these fish can start to feel mundane if you eat them week after week. In search of an exciting alternative, you may have come across swai fish—but what exactly is swai fish, and is it OK to eat?
We tapped nutrition and fish experts to speak to swai's health benefits, environmental concerns, and mislabeling issues. Here's what to know about the pros and cons of swai fish—and why you may be better off going with another option.
Swai fish nutrition
Firm in texture and mild in flavor, swai is a freshwater fish native to Southeast Asia.
The fish is primarily farmed (rather than wild-caught) in Vietnam, though it's also produced in Thailand, Nepal, Pakistan, India, Bangladesh, Laos, Myanmar, Indonesia, and Cambodia, according to Athena Davis, the North America marketing manager for the Aquaculture Stewardship Council (ASC).
"It's pretty popular in the U.S. as well as some other markets around the world for being a more affordable option for seafood," says Maggie Moon, M.S., R.D., a Los Angeles–based registered dietitian and the author of The MIND Diet. "People may also be seeking it out because it's a lean protein and fish [in general] is good for the heart and the brain."
You may not always see the fish labeled as "swai" in grocery stores or restaurants, though. The fish, which is scientifically known as Pangasianodon hypophthalmus, is also known as pangasius, basa, striped catfish, striped pangasius, and tra, says Corbett Nash, the outreach manager for the Monterey Bay Aquarium Seafood Watch program.
Although it's a type of catfish, the U.S. Food and Drug Administration doesn't permit it to be labeled as such in this country; instead, it's called sutchi catfish, he adds.
Compared to other white fish, swai is lower in calories and fat; a four-ounce serving of the fish contains 0.5 gram of fat, while tilapia and halibut provide 2 grams and 5 grams, respectively. Swai's protein levels are on par with its counterparts, offering 1 gram less than tilapia and just over 2 grams more than halibut.
|Fat||0.5 grams||2 grams||5 grams|
|Fiber||0 grams||0 grams||0 grams|
|Protein||19 grams||20 grams||16.6 grams|
|Calcium||13.4 milligrams||10 milligrams||14.4 milligrams|
|Iron||0.10 milligrams||0.5 milligrams||0.6 milligrams|
|Potassium||385 milligrams||0 milligrams||378.4 milligrams|
|Sodium||30.2 milligrams||52 milligrams||267.2 milligrams|
|Cholesterol||50.4 milligrams||50 milligrams||47.2 milligrams|
Benefits of swai fish
It contains a nutrient that protects against oxidative damage.
Of all the nutrients swai contains, selenium is the standout, says Moon.
A trace mineral, selenium plays a role in reproduction, thyroid hormone metabolism, and DNA synthesis5. Perhaps most importantly, says Moon, it helps protect the body from oxidative damage and infection.
"Selenium is heavily involved in our antioxidant system in our bodies, so it's very important to our antioxidant defenses and helps lower oxidative stress in the body," says Moon.
And this can have significant health implications, as oxidative stress can contribute to the development of conditions such as cancer, cardiovascular disease, and neurodegenerative diseases6 if left uncontrolled.
It supports brain health and mood.
"Omega-3s are anti-inflammatory, and they help keep the cell membranes of the neurons in your brain healthy," Moon explains. "The brain is 60% fat, and the omega-3 fats specifically keep it running optimally."
What's more, seafood like swai fish contains B vitamins, including vitamins B6 and B12, which are involved in producing serotonin and dopamine8—neurotransmitters that make you feel calm and happy, says Moon.
It's beneficial for heart health.
With zero grams of saturated fat and just half a gram of total fat, swai fish is considered a lean protein. And, in turn, the fish can have heart-health benefits when eaten in place of higher-fat proteins, says Moon.
When consumed in excess, saturated fatty acids—found in large amounts in red meat and cheese—increase low-density lipoprotein (LDL or "bad") cholesterol, which raises the risk of cardiovascular disease9.
However, consuming higher amounts of fish—which are generally lower in saturated fat—has been significantly associated with a lower incidence of coronary heart disease10.
Risks & side effects of swai fish
While swai offers some health benefits, it also comes with some major health and environmental concerns. It's also less nutritious than other fish you'll find on the market. Here's what to know.
It contains lower amounts of omega-3s than other fish.
A standard serving of swai offers roughly 19 milligrams of omega-3 fatty acids, which is on the low end of the 250 to 500 milligrams of combined EPA and DHA (the types found in marine sources) most experts recommend daily, says Moon.
Swai farms can generate high amounts of waste.
"The ASC's Pangasius Standard includes strict requirements on monitoring water quality and limiting environmental impacts of feed ingredients and waste, among many others," says Davis. "For example, ASC-certified swai farms are required to measure various water parameters (nitrogen, phosphorus, oxygen levels, etc.) on a regular basis and remain within set limits. Treatment systems for waste and sludge need to comply with strict requirements before discharging can occur."
Uncertified swai can come with environmental risks, which is why the Seafood Watch recommends avoiding it. Uncertified swai farms in Vietnam have been linked with large volumes of effluent waste, which could include the fish itself, scales, chemical inputs, or uneaten food, notes Nash.
Many of these farms reportedly engage in illegal dumping, he adds. "Illegal or not, the effluent is beyond the scale that we consider reasonable on these farms," he says. "If the effluent is not treated to some degree, it's often not very healthy to the surrounding environment."
High amounts of chemicals may be used in production.
Another red flag: Data on chemical use (often for controlling parasites and disease) at uncertified swai farms in Vietnam is not available, says Nash.
FYI, for pangasius, ASC allows only the use of antibiotics after a diagnosis by an aquatic animal health specialist and a prescription, and there must be a withdrawal period to prevent residue on the final product. Certified swai farms are also limited in the type of antibiotics they can use, says Davis.
Swai farming may pose threats to wild populations.
"Outside of the potential environmental impacts farming can have on local biodiversity if done irresponsibly, farmed fish can affect wild populations if they escape," says Davis. "They can compete with wild fish or breed with them and impact the genetic makeup of wild populations."
To avoid this, ASC-certified swai farms need to have plans in place to prevent escapes, such as regular pond maintenance, timely inspections, and barring wild-caught or GMO juveniles into the breeding program, she notes.
Alternatives to try
Turned off by the sustainability concerns surrounding swai? There are plenty of other mild, affordable fish that come with a smaller environmental impact and even more favorable nutrition profile. Here are a few:
A white fish with a mild flavor, barramundi is rich in omega-3s, offering 650 milligrams per serving, says Moon. In a 113-gram serving, barramundi also provides12 more protein (23.1 grams) and fat (roughly 1 gram) than a similar-size serving1 of swai. Plus, the fish generally has a smaller environmental impact than pangasius.
When farmed in indoor recirculating tanks, there tends to be low chemical use, and although producers can release a portion of their daily water flow without treating or disinfecting it, the risk of disease transmission to wild species is low, according to the Seafood Watch program.
Most catfish in the U.S. is farmed rather than wild-caught, and fish farms in the country are tightly regulated, says Nash. "They do a good job at dealing with the effluent and keeping chemicals under control," he notes. The nutritional profile is pretty similar to swai, as well.
A 113-gram serving of blue catfish offers the same amount of protein (19 grams) but greater amounts of fat13 (nearly 3 grams, the majority of which is unsaturated) compared to swai.
Wild-caught Alaska pollock is sustainability managed and responsibly harvested under U.S. regulations, according to the National Oceanic and Atmospheric Administration (NOAA).
Avoiding fish fraud
The complicated nature of the global seafood supply chain means that you can't always guarantee that your fish has been accurately labeled.
30% of the marine fish that is caught around the world is either illegally caught or unreported
"There's a significant amount of illegal, unreported, and unregulated seafood that gets laundered into the supply chain," says Max Valentine, Ph.D., the campaign director of Oceana's illegal fishing and transparency campaign in the United States. "Globally, it's estimated that as much as 30% of the marine fish that is caught around the world is either illegally caught or unreported."
What's more, seafood fraud is common. One investigation found that an average of 22% of seafood products were mislabeled—meaning they were not the product being represented to the consumer, says Valentine.
It's important to note that the FDA and NOAA both regulate seafood: The former requires nearly all seafood products to meet certain recordkeeping and traceability standards, and the latter has the Seafood Import Monitoring Program that traces food from the boat to the U.S. border, she explains. The problem: Siluriformes (aka catfish—including swai) are excluded from both of these administrations' mandates, says Valentine.
As a result, "swai and other forms of Siluriformes have been frequently found to be substituted for higher-value fish in numerous seafood fraud studies," says Valentine. "There was a global review a while ago of seafood mislabeling studies, and Siluriformes were found to be the most commonly substituted fish worldwide; they were being sold as a wild-caught or higher-value fish than they actually were."
Not only does this mislabeling hurt consumers' wallets, but it also increases the risk of being exposed to products that haven't been held to certain food safety standards, contain high mercury levels, or are linked with forced labor, says Valentine. "No one wants their order of fish and chips to come with an additional side of human rights abuses," she says.
How to avoid fish fraud
If mislabeling is so common, how can you guarantee that you're getting the fish you think you are? Here are a few tips for avoiding seafood fraud at the supermarket or restaurant.
Before you hand over your credit card or place your order, ask the individual who's selling you the seafood where the fish is from, the species name, and any certifications (such as those from Aquaculture Stewardship Council or Marine Stewardship Council) it has, says Valentine. If you're able to, look directly at the label.
"Oftentimes, you'll see packaging on the front that talks about a product and where it's from, and then you flip to the back and you see it's a product of another country," she says. "Really take the time to digest labels and confirm that you understand what you're purchasing."
Don't be blinded by a low price.
"If the price of something is too good to be true, then it probably is," says Valentine. "If something has a really, really low price per pound that seems uncharacteristic of that product. then there's probably some inherent risk with that product."
These risks shouldn't scare you away from eating fish—they are chock-full of health benefits, after all. But you should be cautious when purchasing your dinner, regardless of the species, says Valentine.
Is swai fish healthier than tilapia?
Swai and tilapia have similar nutrition profiles. The fish provide 19 and 20 grams of protein, respectively, and both have small amounts of fat. Like swai, tilapia contains low levels of omega-3 fatty acids: a 3-ounce serving boasts 100 milligrams of DHA and 6 milligrams of EPA, according to the University of California, Davis.
Is it healthy to eat swai fish?
Swai fish can be a healthy addition to your plate, particularly when it's eaten in place of other higher-fat proteins. The fish is low in fat, high in protein, and offers benefits for your brain and heart health. However, it's much lower in omega-3s than other fish and is often mislabeled.
Is swai a high-mercury fish?
Swai is considered a low-mercury fish, according to a 2014 study on 77 finfish species. The researchers found that pangasius contained 2 parts per billion of mercury, notably less than Atlantic cod (82 parts per billion) and salmon species (13 to 62 parts per billion).
Swai fish is a lean protein that's high in selenium, and it may help reduce the risk of cardiovascular disease, especially when it's consumed in place of red meat. That said, swai contains small amounts of omega-3 fatty acids compared to other fish, and there are concerns surrounding its environmental impact and mislabeling. To ensure you're getting a sustainably farmed, properly identified fish, look for a certified swai product. Or better yet, go for a healthier and more environmentally sustainable seafood option instead.
Megan Falk is an experienced health and wellness journalist whose work has appeared in publications such as SHAPE.com, Health.com, LIVESTRONG.com, Equinox, DoctorOz.com, and SAVEUR magazine, among others. Most recently, she was the assistant editor at SHAPE.com, primarily covering exercise tips, fitness modalities, workout trends, nutrition, and more.
Megan is a graduate of Syracuse University's S.I. Newhouse School of Public Communications with a bachelor's degree in Magazine Journalism and a minor in Food Studies. She's also a certified personal trainer through the American Council on Exercise.