Swayfish Facts

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The swai fish, also known as the rainbow shark, is a type of shark catfish native to Vietnam.

These omnivorous benthic animals live in the Mekong River and migrate upstream when water levels rise in late summer.

When left alone, iridescent sharks can grow up to 100 pounds. Commercial farmers often raise large quantities of swai to sell as a popular substitute for catfish meat. You can also find stunted, iridescent baby sharks as aquarium pets.

3 Unbelievable Swai Fish Facts!

Swai fish in the aquarium
The name "iridescent shark" refers to the shimmering sheen around the edges of the shark's fin that can be seen even in the dark.

©Ollga P/Shutterstock.com

  • Glowing fins: The iridescent shark gets its name from the edges of its fins, which glow brightly even in the dark.
  • Endless Appetite: Swai will eat almost any food they come across. Plants, crustaceans, and smaller fish are no match for the iridescent shark's omnivorous appetite.
  • Shark Fin Style: Swai is a type of pangasius or shark catfish. Although they're not actually sharks, these catfish have dorsal fins and a silvery sharklike appearance.

taxonomic name

Swai fish in the aquarium
The scientific name of the swai fish is Pangasianodon hypophthalmus .

© CHAINFOTO24/Shutterstock.com

The scientific name of the swai fish is Pangasianodon hypophthalmus . In Vietnam, they are often called tra fish; they may also be mistaken for the related basa or Pangasius bocourti . When they're not sold as livestock, these silvery creatures are often called rainbow sharks for their glowing fins and shark-like appearance.

The iridescent shark belongs to the rayfin and catfish families of the carcharids. They are related to the American catfish, but they are distinguished by their shark-like dorsal fin. Regarding their scientific name, shark catfish are also often referred to as pangasius by members of the research community.

evolution and origin

Swai fish swimming in the pond
Although swai originates from the Mekong River in Asia, most swai available for purchase comes from fish farms in Vietnam.


Swai is native to the Mekong River in Asia, but most of the swai that people can buy comes from fish farms in Vietnam. In fact, Vietnam, located in the Mekong Delta, has one of the largest agricultural swai industries in the world.

Swai fish and other fish imported from Vietnam are often considered "unclean" and cause many health problems due to variable quality. Most of the swai fish (Basa) brought into the United States is native to Vietnam.

Also, it is recommended to stay away from Swai fish as it has poor nutritional content. It is imported from densely populated fish farms that use excessive amounts of pesticides and antibiotics, polluting the environment and endangering human health. Sometimes it is marketed as a more expensive fish.

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Different types

Several names are used to refer to swai fish such as tra, striped pangasius, Vietnamese catfish, striped catfish, rainbow shark, sutchi, and basa. There is only one of this type.


The iridescent shark is an Asian catfish with silvery scales, beige skin and a small whisker. Like other shark catfish, pangasius has a small dorsal fin on top of its body. The edges of the pangasius' fins glow faintly underwater, making them a popular choice for aquariums.

Juvenile rainbow sharks can grow to be 1 to 4 feet long and usually weigh between 50 and 100 pounds. The largest swai fish ever recorded weighed 44 kilograms or about 97 pounds.

Diets or confined spaces can hinder pangasius growth, which is why iridescent sharks living in aquariums are often much smaller than wild or commercially farmed sharks.

Swai fish in the aquarium

© CHAINFOTO24/Shutterstock.com

Distribution, Population and Habitat

Rainbow sharks are native to Asia and are most commonly found in Vietnam. Most wild pangasius live in the Mekong River, where they travel upstream from the Mekong Basin. Some pangasius also swim downstream into the Chao Phraya River.

Pangasius is a freshwater fish that is commonly farmed in ponds, rice fields and similar structures. Almost all rainbow sharks sold commercially are raised as livestock; you should not expect to buy wild pangasius in normal markets.

While population numbers are not available, the rainbow shark is considered endangered in its natural habitat.

predator and prey

Rainbow sharks are omnivores, feeding on crustaceans, algae, insects and other small fish. At full size of 100 pounds, a swai will eat just about anything it can get its hands on. When commercially farmed, pangasius typically feed on barley, oats, and other types of grains.

Pangasius have no natural means of self-defense, making them popular targets for all predators in their native range, including birds, mammals and other large fish. Human fishermen are one of the main threats to rainbow sharks, and overfishing may be responsible for their current endangerment.

Reproduction and Lifespan

Iridescent sharks are spawning creatures that live in large colonies. Like other species of catfish, pangasius reproduce in a migratory pattern that involves swimming upstream to breeding grounds during the late summer months.

Due to their feral nature, iridescent sharks are particularly difficult to reproduce in captivity. Pangasius farmers tend to keep this fish in large ponds with many other members of the same species to ensure adequate breeding conditions. Because of the lack of research on this particular fish, it's unclear how long swai can live in the wild. In captivity, a beloved iridescent shark can live up to 20 years.

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fishing and cooking

Although iridescent sharks are found naturally in Vietnam's rivers, most commercial swai production takes place in controlled farming environments. Large schools of pangasius are raised in ponds, rice fields and other bodies of water until they are large enough to be harvested for consumption.

In cooking, swai meat is used as a popular substitute for American catfish. The flavor is described as sweet and much milder than their catfish cousins. Swai is known to have a firmer texture and a slightly milder taste than basa, another shark catfish found in the same area.

Swai meat is a good source of protein and vitamin B12. Unless you live in Vietnam, chances are you'll find pangasius flesh in the freezer section, where it stays fresh and tasty for up to a year at a time. Frozen pangasius can be baked, baked or fried for the best texture. Remember to thaw frozen fish before cooking to prevent excess moisture from entering the dish.

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Swai Fish FAQs (Frequently Asked Questions)

Where can I find swai fish?

Rainbow sharks are found in the wild across Asia, but they are thought to be native to the Mekong River in Vietnam. Commercial catfish are often raised in ponds and other types of local fish farms.

what is fish

The rainbow shark is a catfish native to Vietnam. Swai meat is often sold as an alternative to American catfish or the slightly more expensive pangasius.

Is swai fish high in mercury?

Iridescent sharks are relatively low in mercury. A study of commercially available pangasius found mercury levels of just 2 parts per billion.

Is swaifish banned?

Rainbow sharks are not banned from sale or consumption anywhere in the first world as long as they are properly labeled. However, it is illegal to market pangasius as catfish in the United States.

Is swai fish safe to eat?

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Swai meat is considered safe to eat and is a popular protein choice in many markets. However, be aware that any aquatic meat can be affected by questionable farming practices and should be purchased at the discretion of the consumer.

Are Swayfish Healthy?

Swai meat is a relatively healthy protein choice for most diets. Pangasius meat contains a lot of selenium, niacin and vitamin B12.

Swai Fish vs. Pangasius

Swai and basa are both shark catfish native to Vietnam. Basas, also known as Pangasius bocourti, are rarer than swai; they are also larger and usually have softer, more tender meat. Swai is often mistaken for bocourti in some markets.

Are Swai Fish herbivores, carnivores or omnivores?

Swai fish are omnivores, which means they eat both plants and other animals.

To which kingdom does the Swai Fish belong?

Swai Fish belongs to Kingdom Animalia.

What door does Swai Fish belong to?

Swai fish belong to the phylum Chordate.

Which category does Swai Fish belong to?

Swai Fish belongs to the class Actinopterygii.

What family does the Swai Fish belong to?

Swai fish belong to the catfish family.

What order do Swai Fish belong to?

Swai Fish belong to the order Siluriformes.

What type of mulch does Swai Fish have?

Swai fish are covered with scales.

What is the scientific name of the Swai fish?

The scientific name of the Swai fish is Pangasianodon hypophthalmus.

How many types of Swai fish are there?

There is 1 type of Swai fish.

What is another name for the Swai fish?

Swai fish is also known as tranny, rainbow shark or pangasius.

How do Swai Fish have babies?

Swai fish spawn.

What's the difference between swai and catfish?

There are many differences between swai and catfish, including their size and location. Swai is larger than some types of catfish and is found only in Asia, while catfish can be found all over the world.

What is the difference between tilapia and swai fish?

There are many differences between swai fish and tilapia. Both are popular culinary fish, which brings up the comparison, but the swai fish in the wild is much larger. In addition, wild tilapia is found in Africa and swai fish in Southeast Asia.

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  1. VASEP, available here: http://mseafood.vasep.com.vn/panga/724_10857/what-are-biology-characteristics-of-tra-and-basa-fish.htm
  2. Seafood Handbook, available here: https://www.seafoodsource.com/seafood-handbook/finfish/basaswai
  3. Fishbase, available here: http://www.fishbase.us/summary/SpeciesSummary.php?ID=14154&AT=swai
  4. Fish Laboratory, available here: https://www.fishlaboratory.com/fish/swai-fish
  5. National Library of Medicine, available here: https://pubmed.ncbi.nlm.nih.gov/25198598/