This is definitely not a koi, though it could be a hybrid. The head is not quite right for a goldfish, but at that size everything is a little distorted. What a monster!
The largest Goldie in the UK is 38cm. I think Guiness records has one at 47cm from the Netherlands. Now someone finds a Goldie which is 61-71cm, but oops, didn't keep him.... I suppose that's the fish (returned alive to the lake), hanging peacefully with a finger stuck up it's throat. Sorry, looks a Photo-shop to me.