The Loch Ness monster is most likely a large catfish, according to an expert who has spent 24 years searching for Nessie.
Steve Feltham, 52, gave up his home, his job and his girlfriend to move nearer the Scottish loch in pursuit of the legend.
Speaking to Sky News, Mr Feltham did not claim he had solved the mystery of Nessie.
But he said: "Looking at all the evidence, speaking to eyewitnesses, the most likely solution is a Wels catfish."
The fish can grow up to four metres (13ft) long and weigh over 400kg (880lb).
There have been various photographs over the decades of a strange object in the water, leading to claims of a monster there.
One infamous black and white picture of a head and neck peering out of the water in 1934 was later revealed as a hoax by one of the people who staged it.
Mr Feltham claimed that sonar contact had picked up objects in the loch that were the size of an estate car.
This was even though the biggest creatures known in the loch were salmon and seals that sometimes chase them.
"We get sonar contacts with things that are far bigger than any fish that should live in this body of water," he said.
And he admitted: "We only get one or two decent sightings a year."
Mr Feltham said he had no regrets about dedicating nearly a quarter of a century of his life to try to solve "one of the world's greatest mysteries".
"I'm in my utopia living here on the shores of the loch," he said.
He holds the record for the longest continuous vigil hunting for the Loch Ness monster and he predicted he could continue his search for another decade.
He said: "I'm not saying the mystery's solved. I'm still looking for a better explanation than that (Wels catfish).
"This is an explainable phenomena. There is something to be explained in Loch Ness."