A rare and alien-like sea creature has washed up on the shore of a popular Australian beach, leaving tourists stunned.

The beast, known as an ocean sunfish, was found by tourists at the mouth of Kennett River on Victoria’s south-west coast on Saturday.

Cath Rampton and her husband Tom, who are both vets, said they were shocked when they came across the huge fish, which neither of them had seen before.

Vet Cath Rampton found the alien-like sunfish fish washed up at the mouth of Kennett River on Victoria’s south-west coast on Saturday

Ms Rampton told Daily Mail Australia the fish measured around two metres in length and height, but it was still small for its species.

‘My understanding is it’s not a very big specimen, I think they can get up to double that size,’ she said.

Ms Rampton added that seeing the fish was an amazing surprise.

Tourists Tim Rothman and James Barham found the sunfish days after it was first discovered and said it looked like ‘an alien from a distance’

Tourists Tim Rothman and James Barham found the fish on Monday and described it as ‘alien’ in appearance.

‘We were walking along and saw this big lump on the sand,’ Mr Rothman told the Geelong Advertiser.

‘I’ve never seen anything like that before. It looked like an alien from a distance.’

Mr Rothman said he had frequently visited Kennett River over the years and doubted he would ever see a fish like it again.

A sunfish was previously found by fisherman last year near the mouth of the River Murray – a popular fishing and holiday destination in South Australia.

That sunfish was estimated to be around 2.5m in length and weighed several hundred kilograms.

Sunfish can grow up to 3m long, 4.2m high and weigh up to 2.5 tonnes.

They are considered vulnerable in the wild, making the find even more incredible.

Ms Rampton said the fish measured around two metres in length and height but it was still one of the small ones. Pictured right is her daughter Penny, aged seven

Last year fishermen found a huge sunfish along the South Australian coast with an estimated length of 2.5 metres

Fish collection manager Ralph Foster, from the South Australian Museum, previously explained why so many sunfish get washed up on the beach.

‘One of the big dangers would being hit by big boats at sea,’ he said.

‘They often eat plastic bags thinking they are jelly fish which can kill them.’

Sunfish wash up on South Australian shores quite frequently, Mr Foster said he received reports of several every 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 confused for sharks due to their fin.

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

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