The irridescent shark is actually not a shark at all but a catfish from SE Asia. The correct scientific name seems to be Pangasius hypophthalmus, but most of the hobby literature refers to them as P. sutchi which is no longer a valid name. They belong to the family Pangasiidae. They are found in Viet Nam, Thailand, Laos, and Kampuchea.

The are not good aquarium fish! A large adult may reach 1.3 meters and weigh 15.5kg. They are also very active and should be kept in shoals. They are nervous in captivity and the noses of those that are kept in captivity are invariably severly deformed from constantly ramming the sides of the aquarium. A proper set up would contain atleast six individuals and be atleast 20 feet long by eight feet wide. They are bred throughout Asia as food fishes. They are bred in large shallow ponds. I am not sure if they breed "naturally" in these ponds or if hormones are injected to induce spawning. If you have not bought one, then don't! If you already have one take it back and trade it for something that you can provide a proper habitat for.