Schoolboy angler Nick Richards struck gold when he reeled in this enormous bright orange goldfish.

Nick, 16, was fishing for carp when he caught the supersized fish, which weights 5lbs, is 16 inches long and is believed to be the biggest ever in Britain.

It is thought it was abandoned in a lake at Upton Heath in Poole by its owner after outgrowing its tank and has rapidly expanded in size since.

Nick, from Camberley, Surrey, said: “My family have a holiday home in Poole and I come down as often as I can to go fishing.

“I was there for two days running and caught some big common carp.

“Then suddenly I saw this big orange fish cruising along the top of the lake.

“It wasn’t too much trouble to reel it in. At first I thought it must be a really fat koi carp, but when I saw it properly I realised it was a common goldfish.

“The only difference was that it was massive.”

He added: “It looked like it was healthy and in good condition. The lake is sheltered with plenty of food, so it’s doing pretty well.

“Earlier in the day I’d joked that if I caught a big fish I’d call it Billy, so of course the goldfish got the name.

“I put him back in the lake straight away. Some people have said that if I do catch him again, though, it might be an idea to give him to someone who has a big tank.”

Ruth Lockwood, from the English Carp Heritage Organisation, said: “It seems most likely that it was released into the lake by someone after it outgrew a tank or pond.

“Hobbyists must be reminded that it is illegal to release pet fish into the wild – it is a crime. It has a massive impact on the environment and our native species and must not be encouraged.”