There are plenty of fish in the sea, so goes the saying – but not many look like this freaky fella.

The bizarre trout appears to have two mouths.

Angler Debbie Geddes was shocked to hook the apparent mutant while out on Lake Champlain in Plattsburgh, New York.

When she posted pictures of the unusual creature to Facebook, it inevitably went viral, with dozens of respondents offering theories on how a fish comes to have a double decker mouth.

“When it bit, it felt like I had a nice fish on,” wrote Ms Geddes who herself lives in Plattsburgh. “I actually commented, ‘I hope it’s as big as it feels’.

“When we got it in the boat I couldn’t believe what I was seeing! Two mouths! And yet this fish was healthy and thriving! Pretty amazing! We quickly took a few pictures and released the fish.”

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Her colleague, Adam Facteau, saw the photos and posted them online to the Knotty Boys Fishing Facebook page – and they have since been shared more than 5,000 times.

“I just can’t believe all the attention this has received,” Ms Geddes said. “The public’s responses and theories are quite interesting. I personally believe it was caused by a previous injury, most likely from another angler.”

Among those theories were respondents who said the mutation may have been caused by a birth defect or by pollution

Some locals suggested it could be related to Champy, a mythical 187-foot long monster believed to live in Lake Champlain – although with the trout weighing in at just six pounds the comparison seemed a little far-fetched.

But the true cause may be a little more mundane: ripped muscle and skin.

“All fish have, behind their jaws, a set of gill arches and a hyoid arch,” Dr Ralf Britz, a fish researcher at London’s Natural History Museum told The Independent.

“What appears to have happened to this fish – either through a birth defect or more likely an injury at some point – is that the skin and muscle which covers these arches and connects them to the lower jaws has been lost and left the skeletal structure exposed.

“It looks unusual but this is what all trout have under their skin and muscle.”

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