Sustainably-farmed Murray cod is in high demand at top end restaurants across the country and growers are ramping up production.

The native Australian freshwater fish is a renowned icon of the Murray River, where the species made headlines as up to a million of the fish were killed this week in their natural habitat after a toxic blue-green algae outbreak.

As a farmed fish though, out of the river, the species is highly sought after as one of the most expensive in Australia.

Farmer Brenton Parker from Renmark in South Australia diversified from growing wine grapes to farming Murray cod nine years ago and said despite initial challenges he is now reaping the rewards.

Fresh Murray Cod fish is renown for its distinct flavour. ( Supplied: Brenton Parker )

"Demand is growing every day and I am going to double my size in the next two years," he said.

Farmed Murray cod is loved by chefs and consumers for its pristine white flesh and clean taste.

The fish is a favoured fresh live seafood at Australia's metropolitan markets and sought after especially in Asia.

Prices for fresh Murray cod currently sit at $20–24 per kilogram.

Mr Parker said he was only a small-scale Murray cod farmer in comparison to operators in New South Wales, but was planning to expand his 200,000-litre operation tenfold in the next eight years.

"I produce around five–seven tonnes per year but my long-term plan is just to keep growing and hopefully, I'd love to see 50 tonnes a year," he said.

Murray cod renown for unique taste among chefs

Head chef at the Loxton Hotel in South Australia Greg Janssen said Murray Cod was a pristine product for which more and more consumers were getting a taste for.

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"When you eat a lot of fish that comes straight out of the river, it can have a quite muddy taste and the fat in the fish can have a quite muddy taste," Mr Janssen said.

"Yet, this cod is farmed here and it actually isn't in the Murray River, it's only fed through Murray River water, so you don't get that muddy taste at all.

"So the meat itself then becomes pristine, it's absolutely white and it's got a really fresh flavour, which people seem to really like."

Mr Janssen says they chargrill the entire Murray Cod at the Loxton Hotel. ( Supplied: Loxton Hotel )

Mr Janssen said at the restaurant they butterflied the fish, took all the bones out and then chargrilled the flesh to get open-flame flavours.

"It's really good for the cod because it's like if you were down the river and you had an open fire and you're just grilling it, the flesh takes those flavours on really well," he said.

Mr Janssen said they were lucky to be situated on the Murray River and did not struggle for supply, but that they received a lot of calls from restaurants in the Northern Territory, Alice Springs and Adelaide trying to source the fresh fish.

"You literally can't get in fresher here unless you've pulled it out of the water yourself," Mr Janssen said.

Head chef Greg Janssen catching fresh Murray Cod for their menu. ( Supplied: Loxton Hotel )

"We get the fish fresh and have to scale and gut it ourselves, which has been very interesting because I had to teach a lot of chefs how to do it.

"It's an art that has been lost and there aren't too many chefs that take a fresh whole fish that's actually alive when they get it and go through the whole process."

Waste water reused on crops

Farming Murray cod is a diverse income stream for farmers in Australia's inland aquaculture and the double use of water, makes it an efficient industry with a small environmental footprint.

Mr Parker said all the waste water he had to go through was used to irrigate his wine grapes.

"I go through 25,000 litres a day, so I reuse it to water about seven acres of vineyard," he said.

Mr Janssen said they used many locally grown products such as shallots and herbs, which were watered with the waste water of the farmed Murray cod.

"So, you are getting double benefit from the use of one lot of water, instead of just watering something and then it grows and its gone," Mr Janssen said.

Brenton Parker is breeding his own fingerlings for the first time this season. ( ABC Rural: Jessica Schremmer )

Mr Parker said in previous years he used the water to grow crops in aquaponic systems but now set focus on breeding his own fingerlings to grow the fish.

"Usually I collect eggs and send them to a hatchery but this season I am trying to do it myself, so hopefully I can do it all here on farm in South Australia," he said.