Looks like a Gigas to me. I'm extremely jealous I must say, I'd kill to have 1-2 of them. Here is a pic of a paroon at similar size to show that it is not pangasius santiwogesi. Best way to tell is look at the placement of the eye on the gigas its towards to the bottom of the fish whereas most pangasius have their eyes pretty much mid way between top and bottom. Also look at the shape and location of the pelvic fins, the gigas is more towards the anal fin where the paroon is closer to the pectoral fins and also the gigas is more of a nub. The paroon has a clear contrast between black and silver/white and is more elongated.