Be happy to...............
The irridescent shark or Pangasius hypophthalmus (scientific name), but is better known as P. sutchi in the hobby is found in locations such as Viet Nam, Thailand, Laos and Kampuchea.
They are nervous fish when kept in aquariums and many times you will see deformaties of the nose due to ramming themselves into the side if the aquarium due to this nervousness.
They are best kept in shoals of at least 6, but their adult size of 1.3 meters (4ft + ) and weighing 15.5 kg (34 pounds) makes this all but impossible, and therefore makes them totally inappropriate for the home aquarium.
Irridescent sharks should not even be offered for the aquarium trade due to these facts.
Note* They are bred is Asia as a food fish in large ponds!!!
Hope this answered your question as to whether or not to take it back!! While it is doubltful yours will attain it's probable adult size, it will not be comfortable and therefore will be under constant stress.
CM