Another fresh war is brewing between Australia's supermarket giants. From fresh produce, Coles and Woolworths are now battling for the title of being the number one supporter of sustainable fish species.

Coles announced over the weekend that it would no longer sell unsustainable breeds of fish by placing "Sustainable Choice" stickers on its fresh, wild-caught fish in an attempt to boost its green credentials.

Coles and Woolworths had banned in the past endangered fish such as yellowfin tuna and orange roughy from its shelves. Coles upped the ante by promising to phase out all unsustainable species by 2015.

"We're taking the guesswork out of buying sustainable fish.... Customers want to do the right thing, but it's not easy to figure out what is sustainable and what isn't," Coles spokesman Jon Church said.

The new policy is expected to boost Coles' sales by another 20 per cent and coincides with the approach of Lent and Easter which is a time when fish sales rise by 85 per cent because of Catholic tradition of abstaining from animal meat during all Fridays of Lent.

Coles has for its partner the World Wildlife Fund (WWF) to set fishery standards while Woolworths linked with the Sustainable Fisheries Partnership Foundation in a bid to get an international accreditation from the Marine Stewardship Council.

Coles asked WWF marine scientists to investigate 300 types of fish it sold. After a year of investigation, the WWF showed Coles sold 33 species that were unsustainable. Among the 33 were local snapper, calamari, garfish and sardines caught in Victoria's bays and inlets.

Coles said it would concentrate on sourcing its fish from farm ponds and frozen species and crustaceans.

"With WWF having now reviewed all of our fresh-caught fish, we can confidently tell customers which of their favourite fish are not only great quality but also caught in a more sustainable way," Mr Church said.

Fishmongers, however, labeled Coles' campaign as a big gimmick.

"Their product will never be as good as the fresh fish we sell at the market," the Herald Sun quoted fishmonger John Kyzintas who owns stalls at Queen Victoria and South Melbourne markets.

Unlike Coles and Woolies' fresh milk and fruit and vegetable price war which affected local farmers, fishmongers are not alarmed by the move of Coles.

Paul Thomas, who owns Point Cartwright, said it would be difficult for the two supermarket giants to supply fresh seafood. The Mooloolah River Fisheries group added that they are not bothered by the marketing gimmick because the bulk of fish sold by Coles and Woolies are imported ones.

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