Since the mystery was exposed in The Press last week, dozens of interested readers have called in to tell us that it was a Ray's bream, with pensioner Dennis Nedey (65), who discovered it on the sands also receiving many calls.

Mr Nedey, of Winifred Crescent, said: "The response has been amazing and I am very grateful to everyone who has taken the time to contact myself and The Press with their views."

The large silver grey fish are not normally found in the Forth, but over the last few weeks dozens have been washed up on shores along the north east coast of England and the east coast of Scotland.

They are more normally found in deeper waters from the Mediterranean up to Scandinavia, so have come well of course to end up in the estuary.

Staff from Deep Sea World were called in when one of the fish was washed up on the beach at North Queensferry recently and the discovery sparked fears that it could be a pirhana.

Ray's bream can measure up to a metre long and are normally found in water up to a kilometre deep.

Workers at the aquarium believe the creatures may have followed their prey inshore.

Deep Sea World's Michael Morris said: "In the last few weeks a number of Ray's bream have been spotted in the Firth of Forth and there has also been another specimen washed up at Torness.

"We've had reports of many more washing up along the north east coast of England and in other parts of Scotland.

"They're fascinating looking fish and have been compared in appearance to piranhas because of their rows of razor-sharp teeth.

''However they pose no threat whatsoever and are not a danger."

The fish, which can weigh more than five kilograms, are also known as Atlantic pomfret.

Mr Morris added: "They're actually found from the Mediterranean up to Scandinavia although do not usually travel close to shore. Periodically they wash up in large numbers on our coastline.

"No one is entirely sure why but they do appear to migrate in small shoals in response to changes in sea temperature.

''It may be that they come inshore while following large shoals of smaller fish or other prey."