As you guys know, this species is one of the largest catfish species in the world. It reaches almost 3 meters (10 feet) and 300 kg (650 lb?). I wonder who in the right mind will buy these catfishes
. Well, unfortunately, many idiots might be interested in them 
. I'm Japanese and love my country and citizens here, but the morality here involving aquarium, I'm afraid, is not very pleasing. Many buy the young of the large species without planning ahead and end up "releasing" to the wild or the fish die prematurely and miserably in too small enclosure. I always feel devastated when I see Arapaimas sold at pet shop in Japan. They're forced to travel long way from great Amazon and end their life with claustrophobia here. Same could be said to Wels catfish. I can't necessarily follow 4L x 2L x 2L rule for large fish (I try to achieve 3L x 1Lx 1L minimum), but at very least they should aim for 2L x1Lx 1L, which is impossible for Pangasianodon gigas because it would the same size as a whole house. And, even that kind of space is too small for this active,free swimming catfish. I can only pray for the wellness of these poor catfish. Amen