Two fishermen got the scare of their lives when they stumbled upon a huge sunfish stranded on a deserted beach.

They found the creature 25km east of the mouth of the Murray River, a popular fishing and holiday destination in South Australia.

Supervisor Steven Jones saw him while he was out with his fishing team at Goolwa Pipico.

The sunfish was estimated to be around 2.5 m long and weighed several hundred kilograms.

Linette Grzelak posted the image of the fish on Facebook after her partner, who was on the fishing trip, returned home. Hunter and Steven Jones in the photo

Linette Grzelak posted the image of the fish on Facebook after her partner, who was cockle fishing, returned home.

“A sunfish found by my mate along the Coorong a couple of nights ago… I thought it was fake,” she said.

“They thought it was wood while they were driving,” she added.

The sunfish can grow up to 3m long, 4.2m tall and weigh up to 2.5 tonnes and is considered vulnerable in the wild, making the find even more incredible.

The Sunfish was approximately 2.5 m long and weighed several hundred kilograms.

Many of the experienced anglers in the group said they had never seen a sunfish in Australia before.

They are found in tropical waters around the world and are often mistaken for sharks because of their fin.

The large fish is considered a delicacy in some parts of Asia, including Japan, Korea and Taiwan.

Fish collection manager Ralph Foster from the South Australian Museum explained why so many sunfish end up on the beach.

“One of the big dangers would be getting hit by big ships at sea,” he said.

“They often eat plastic bags thinking they are jellyfish that can kill them.”

Sunfish wash up on southern Australian shores quite frequently, Foster said he receives reports of several each year.

“They are actually quite common in Australian waters, but they are generally further out to sea.”

Sunfish are found in tropical waters around the world and are often mistaken for sharks due to their fin (stock).