Hervey Bay fisherman Brett Methven was stunned when he reeled in what appeared to be a giant ‘goldfish’

An angler has joked about reeling in the result of flushing “Fred the goldfish down the toilet as a kid”. Here’s what experts had to say about the deep-sea score.

Brett Methven, an experienced angler, had never seen another fish like it - except maybe a smaller version in a tank - when he landed the 10 kilo bright red fish 400 metres below the surface.

A Hervey Bay fisherman says he was “stunned” when he reeled in what appeared to be a giant goldfish while deep-sea fishing off the coast.

Brett Methven, an experienced angler, had never seen another fish like it – except maybe a smaller version in a family tank – when he landed the 10 kilo bright red fish 400 metres below the surface.

It was later identified as a rare Japanese Rubyfish.

He posted several photos of the fish on his Facebook page after his catch.

“So this is what happens when you flush Fred the Goldfish down the toilet as a kid,” Mr Methven said.

“Our second ever deep dive, we ventured deeper into less than desirable conditions in search of real beasts and we weren’t disappointed.”

Fisheries Queensland described the Japanese Rubyfish as a rare and unusual specimen known for its ability to open its mouth incredibly wide.

The fish uses the unusual ability to suck up zooplankton, bottom-dwelling aquatic animals found 100 to 400 meters below the surface.

While the rare species are found all over the Indo-West Pacific region, there have been only a handful of sightings in Queensland and northern Western Australia.