Giant sunfish washed up on Overstrand beach in Norfolk Published duration 10 December 2012

image caption The giant sunfish washed up on a beach at Overstrand in Norfolk on Sunday morning

A giant fish rarely seen in the North Sea has washed up on a Norfolk beach.

The sunfish, which can grow to weigh up to 2,200 lbs (1,000kg) according to the British Marine Life Study Society, was found dead at Overstrand on Sunday morning.

The fish cannot easily tolerate water temperatures below 12C (54F) and the North Sea in winter is much colder.

It swims on its side on the surface to gain heat from the sun, which is how it got its English name.

The sunfish, genus Mola Mola, from the Latin for millstone which it is said to resemble, thrives in tropical and semi-tropical water, the society said.

'Unusual sighting'

The giant fish's main diet is jellyfish and because of its low mass the sunfish needs to eat many, so it is seen in warmer waters.

They also prey on crustaceans and squid but humans are banned from eating sunfish under European rules because parts of their bodies are thought to contain toxins.

There are frequent sightings of the fish off the south west coast of Ireland and the west coast of Scotland where waters are warmed by the gulf stream but they are rarely seen in winter around the British Isles because the waters are cold.

Jim Ellis, a fish biologist based at the Centre for Environment, Fisheries and Aquaculture Science in Lowestoft, said: "It is likely that the fish was carried along on a Gulf steam. Once in the North Sea, it would have been too cold for it.