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Despite its name, the iridescent shark (Pangasius hypophthalmus) is not a shark, but a catfish. The species is found in Southeast Asia in the Mekong basin as well as the Chao Phraya river, and is heavily cultivated for food there. It has also been introduced into other river basins as a food source and is common in the fishkeeping hobby. It is named for its glow or iridescence.
Food source The fish can be found in the world's supermarkets labelled as basa (though this Vietnamese term refers to several species of shark catfishes). These fish have caused much debate within the political world, with legislation passed recently to prevent basa imports from cutting into American farmed catfish sales. In the wild Iridescent sharks are harmless, schooling fish that prefer to be kept in groups of 5 or more. Adults reach up to 130 cm (4 ft) in length and can weigh up to a maximum of 44.0 kg (97 lb). They prefer large bodies of water similar to the deep waters of their native Mekong river basin. Iridescent sharks are a freshwater fish that natively live in a tropical climate and prefer water with a 6.5 - 7.5 pH, a water hardness of 2.0 to 29.0 dGH, and a temperature range of 72 to 79 °F (22 to 26 °C). Their omnivorous diet consists of crustaceans, other fish, and plant matter. Migration The iridescent shark is a migratory fish that moves upstream to spawn during the flood season while the waters are high and returns downstream to seek rearing habitats when the river water levels recede. The dates of the migrations vary depending on the river system. In the Mekong river basin, they migrate upstream in May to July and return downstream during September through December. In aquariums Juvenile iridescent sharks are often sold as pets for home aquariums. However they are not easy fish to keep and are not recommended for beginners. Accustomed to living in rivers, they are very active fish that require a lot of space. If stressed, their first instinct is to flee, and such a blind dash can result in injuries, especially in an aquarium environment. They also have bad eyesight so they may swim into the glass of a tank and hurt themselves. Many fish owners are unaware of the enormous size that an iridescent shark can reach. If given enough room and fed adequately, an individual of this species can reach 3 feet in length. In most home aquariums, the amount of space an iridescent shark has severely stunts its growth. Therefore, most iridescent sharks kept in home aquaria grow to only six to twelve inches in length. As a rule of thumb, an iridescent shark requires a minimum tank size of 150 cm (5 feet). Schools require even larger tanks. | |||||||||||||||||||||||||||||
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