Swai Fish

The Swai  Fish, or Iridescent Shark, is a rather unremarkable fish that is typically farmed in Asia.  However, it seems to create a bit of controversy in what contexts it appears.  Whether it is to be kept in an aquarium or to be eaten at the dinner table, the Swai Fish has opposing viewpoints.

The Iridescent Shark is not really a shark but gets its name because it resembles on in appearance.   It can be found on the market as Swai Fish and shark catfish.  It is a member of the catfish family.  As a juvenile, the Swai Fish radiates a glow from the edges of its fins, thus given the name Iridescent Shark.   It can grow up to four feet in length and weigh up to nearly 100 pounds.  They are omnivores and will eat other fish, crustaceans, and different types of water plants.  They are either dark gray or black.  In addition to the iridescence, the juveniles usually have a stripe just above the midline that generally disappears in their adult years. 

The Swai Fish is found naturally in Vietnam and the Mekong basin.  They are a freshwater fish and prefer the warm, tropical climate in Asia.  They are found in the Mekong River and Chao Phraya River and prefer the deep waters of large rivers.  The Swai is a migratory fish that swims upstream during monsoon season to breed in the floodwaters.  As the monsoon season ends, the fish migrate to the more shallow waters downstream to rear their young.  Geography seems to play a role in their migratory patterns.  In the northern regions, they travel to the flooded waters from May to July and return to the shallow waters from September to December.  In the southern regions, they migrate to the deeper waters from October to February and are found again in shallow waters in the spring.  The fish are easily bred and is a large provider of food in the region and across Asia. Aqua farmers breed the Swai Fish in muddy freshwater ponds and deliver them worldwide.

The Swai Fish is often found in commercial aquariums and zoos across the world because of their appearance and resemblance to a shark.  However, they are often sold as juveniles in pet stores and aquarium hobby stores as juveniles.  The problems arise when these juveniles as small as 3 or 4 inches will soon grow to be four foot “tank busters” and weigh nearly 100 pounds.  All too commonly, novice aquarium enthusiasts will purchase these fish without researching their physical qualities.  The dealer is anxious for a quick sale.  And the poor fish gets sold and put in a 20 gallon aquarium.  There it will survive perhaps a year if its growth is stunted because of its environment.  When the tank is too small, the fish is susceptible to stress related diseases.  But the fish that continue to grow into adulthood, they are quickly discarded.  They will often eat other fish kept in the tank with them as they continue to grow.  The fish have very poor eyesight and will see any sudden movements as a threat.  As a result, they will dart rapidly seeking protection and injury often results in smaller tanks as the Swai will swim into the sides of the tank or other objects unknowingly.  Fish kept in tanks that are too small will die from organ failure due to not having the adequate resources to mature.  The recommended tank size is 40 feet which is as large as most people’s homes.  A lesson to amateur freshwater aquarists is to do homework before purchasing any fish.

The next area of controversy for the Swai Fish is its safety for food consumption.  Its meat is considered  sweet although somewhat fishy taste.  The texture is very soft and flaky.  Russia is the largest importer of Swai followed by Spain where it is known as Panga.  Many food markets are taking to the Swai fish because it is very inexpensive even though it is considered an endangered species.  The fillets are very light and contain a good quantity of fish oil which are important to controlling heart disease.  Tests performed on the fillets also show low levels of mercury.  Overall, if harvested correctly, the Swai Fish comes highly recommended as an inexpensive and health fish selection.

The controversy comes from the natural habitats of the fish.  The Mekong River is considered to be heavily polluted with dangerous amounts of toxins and chemicals as many factories release their chemical waste into the river.  This, of course, can make for questionable safety for eating this fish as the Swai will eat other fish and plant life in the area.  Also, there are vendors that don’t follow any quality control can make for a dangerous meal.  For instance, there are reports from France that document fish farmers injecting fish with unregulated hormones to stimulate growth.  The fish are often held in cages in the rivers before being harvested.  However, the Swai Fish that are grown in freshwater ponds and farmed in a safe and clean environment are free from the pollutants and toxins.  These fish ponds have filtration systems to help regulate and mimic naturally occurring water levels that the fish enjoy.  These are the fish that consumers need to look for when purchasing fillets at their local market.  Always look at labels and try to identify a large distribution company on the package.  Most reputable distributors won’t be associated with the unscrupulous fish farmers.

The Swai Fish is found in nature in two muddy swollen rivers in South Asia.  From there they have reached into aquariums, supermarkets, and dinner tables around the world.  When the consumer does their homework, the Swai Fish can be avoided as an aquarium fish in a private tank.  It is best left to the commercial display tanks at the zoo or public aquariums.  And for dinner, the Swai Fish is found to be a delicious and healthy fillet.  Again, it is up to the consumer to look for the information on the label and make an educated choice for the best options.

 

Related: Aquaculture in the U.S.

Posted on March 18, 2014 and filed under Freshwater Fish, Guide.