It does look like a wels cat, but there are several other catfish species that get that large. Just from the pic, I'd bet on it being a wel's cat though. It's possible it's a blue cat.
this photo has circulated the web many times. It is not photo-shop'd, it's a record wel's catfish from somewhere in Europe I forget exactly where. Go look up Wel's catfish on the web and you'll find more photo's and stories than you have time for. Kyle