Its a very brightly coloured, and great looking carp. I've caught ones that colour (on a fishing rod :oops:), though much smaller in the Waikato River. Its a very large fish for a koi, but I've no doubt the photo is real. He probably held it out in front slightly to make it look a little bigger. Theres a big fishery for trophy carp in Europe and it think the world record is about 90lb. They very big ones are often a lot uglier than that one. Theres plenty of carp fishing articles on the net with pictures of very big fish.
http://www.dynamitebaits.com/index.php?id=963