It is a fish-eat-fish world for the Murray cod. The endangered and iconic Australian native fish is back on the menu, thanks to new fish farms – if only the cod would stop eating each other.
''These are the sort of fish that don’t play nice,'' said marketer Michael Grinyer of Marianvale Blue, a traditional sheep property turned fish farm outside of Goulburn.
To stop the fish from cannibalising each other, the 500,000 cod being farmed in the company's huge galvanised iron shed are graded regularly. The small are separated from the large to keep the fish size uniform.
Plate-sized: John Breen with a cod that was bred from stock that live in the dam behind him. Photo: Peter Rae
''We have problems in our nursery with the fish being so aggressive,'' said the farm's general manager, John Breen, as he watched a smaller fish being pushed to the top and bitten by the rest of the school.
''You can have a one-gram fish choking and dying on something that’s slightly smaller – say, 0.8 grams.''
The largest of all native fish, cod have grown to more than 100 kilograms in the wild. But commercial fishing and changes in their native habitat in south-eastern Australia caused numbers to fall, prompting a commercial fishing ban and strict limits on recreational fishing. Until recently, farming cod has had mixed success, mostly because of widespread cannibalism when they were bred in farm dams.
Plate size: John Breen holds a fish grown on his property. Photo: Peter Rae
Marianvale, the largest of about 10 NSW producers that are now producing more than $450,000 worth of cod for fish markets and restaurants, has found that tightly packing the cod in the indoor tanks with moving water reduces aggression as it limits their territories.
Cod may not play nice, but the fish is ''delicious'' and has a beautiful succulent texture, said Darren Robertson, a co-owner of the Three Blue Ducks in Bronte. His restaurant is one of a handful, including Rockpool, Sean Moran's new restaurant Tomah Gardens in the Blue Mountains Botanic Gardens and Quay, that has recently put farmed cod back on the menu after many years when it was unavailable.
Mr Robertson said many older diners who knew the fish was endangered asked how it had been caught before ordering, while many younger customers have never tasted it.
Tank to plate: an example of how the cod can be served. Photo: Peter Rae
The wild-caught cod often had a muddy flavour, but the farmed fish now being served with peas, bacon and sea greens was more delicate and ''cleaner on the palate''.
''This is the holy grail for us. We are local and sustainable, and this fish genuinely is.''
The cod will soon be tasted overseas for the first time. Marianvale this week received the first export license for the fish and will exportchilled fish from its shed in a NSW sheep paddock to a plate in China within 24 hours.
Aquaculture: a tank where Murray cod are bred in Marianville. Photo: Peter Rae
The NSW Department of Primary Industries is encouraging aquaculture to meet the demand for the fish, said Graeme Bowley, the department's aquaculture expert. The recirculation tanks used by the cod farmers were unusual because of the high returns per megalitre of water used. He said that while dairy generated $550 return per megalitre of water, viticulture earned $2000, while cod farming and gold mining returned $5000 for every megalitre of water used.
About 90 per cent of Marianvale's water, sourced from bores on the property, is recycled, with fresh water pumped into the tanks twice an hour after it has been filtered through tanks.
''There are real benefits in that,'' Mr Bowley said. ''How many agriculture activities can put the same water back in the crop?''
Back in the day: the fish was plentiful but heavy demand put it on the endangered list. Photo: State Library NSW
Marianvale is also looking to produce its own breeding stock in the future by populating its dams with a small selection of its best fish.
In the wild, rivers are also being restocked, although Mr Bowley said the fish is unlikely to come off the endangered list in the near future.