Motel owner Ross Baker said the image had clearly been altered.
"They've added some steep hills with snow on them to make it look like the Andes, and they're using it quite blatantly to market their Patagonian fishery.
"It's extraordinary because people go from here to there to catch big trout."
To acknowledge his apparent prowess at fishing in the rivers of Argentina, Mr Christmas had now been dubbed "Andre Christobello".
The case became even more intriguing when Mr Christmas appeared to have had major facial surgery, with an image of his body with someone else's head doing the rounds in Bosnia.
"Some guy in Bosnia picked up the picture, put his face on it and has been using it to show everyone what a good fisherman he is," Mr Baker said.
"Now we've turned [Mr Christmas] into a Bosnian: Andro Christovich."
The manager of Argentina's Anglers, Alejandro Pozzi, has apologised for the image, which has since been removed.
"We designed the website and asked them to purchase images with legal rights.
"Apparently [that] was not the case with your picture," he said in a letter.
Mr Baker said it was flattering but dishonest that an overseas fishing operator would choose to use New Zealand trout to promote angling in their region.
"The trout in the picture is normal for here.
"At this time of year already we've had ten-pounders caught, the same size as the one in the photo."
