Following the recent controversy over claims Melbourne fish and chip restaurant chain Hunky Dory has been misleading customers about the fish being served, there have been renewed calls within the industry to introduce mandatory seafood labelling of cooked fish in Australia.

An investigation by The Age found the Hunky Dory chain had been ordering huge amounts of frozen basa fillets imported from Vietnam and instructing staff to call the defrosted fillet "fish of the day dory".

Industry insiders say this misinformation is only the tip of the iceberg of a widespread practice in Australian fish and chip eateries to ambiguously label fish served. Commonwealth Fisheries Association chairman Anthony Ciconte told The Age the incorrect labelling of flake, for example – meant to solely apply to gummy shark or rig shark – is widespread.

"It's not common, it's rife," Mr Ciconte told Fairfax Media. "Incorrect labelling of fish is a systemic issue, right throughout the chain. Retailers are selling fish for $6 or $7 but importing them for $2. The local product would cost about $4 or $5."

In early 2015, Greenpeace launched the Label My Fish campaign – backed by celebrity chefs, academics, Taronga Zoo and Zoos Victoria – saying stronger labelling laws more in line with those in the European Union would encourage the use of sustainable fishing methods, boost the local fishing industry and improve public-health protections.

"Australian labels can be unhelpful and misleading," said Nathaniel Pelle, oceans campaigner at Greenpeace. "It's legal here to label any number of species as 'white fish', when there's no such thing."

Despite the fact that there is an Australian Fish Names Standard in place which clearly labels the correct names to be used, many restaurants, fish and chip shops, cafes and bistros appear to be taking advantage of the fact that use of the standard isn't mandatory for cooked food. While the Hunky Dory chain didn't respond to Good Food's request for comment, they issued a statement which read,

"For the last 11 years Hunky Dory has sold the product Pacific Dory as one of our regular fish-of-the-day varieties. This product has undergone several name changes over the years including Basa, Catfish, and Mirror Dory. There is no clear industry guidelines for the label of this product and so Hunky Dory has continued to sell it under the commonly sold name of Pacific Dory. We acknowledge that this may have caused some confusion so to avoid any confusion for our employees and customers from today we will be clearly labelling our fish-of-the-day product and all our fish in store. Pacific Dory will be clearly labelled as Pacific Dory (Basa)."

This labelling is still at odds with the Australian Fish Names Standard, which lists the correct name of the fish in question as basa and Pacific Dory as obsolete.

Grahame Turk, chair of the National Seafood Industry Alliance, says the industry body is demanding not only that the Australian Fish Names Standard be mandatory, but that country of origin information be included on seafood "right through the chain".

Last year, the cross-bench and Greens attempted to introduce country of origin labelling for cooked and prepared seafood, only to have it voted down by Labor and Liberal senators.

Adam Hanlon, General Manager for Simplot, owners of the I&J brand that supplied the imported basa fillets to Hunky Dory, says his company is always compliant with government authorities when it comes to the manufacture, distribution and sales of food in Australia.

"Our product has the correct labelling as per the ingredient statements on that respective product," he says. "We say the origin because that's a requirement of the Australian authorities. [The basa fillets] are a product of Vietnam and we also state the species as per the correct name on the ingredient statement and we use common names where applicable, [reflective of] the Australian Fish Names Standard."

Hanlon concedes that the so-called confusion regarding fish names need not exist with the Australian Fish Names Standard in place.

"That's the great thing about the fish naming conventions and all the great government authorities being quite stipulated around labelling requirements," he said. "Simplot - and with our branded range of I&J products - comply to that to ensure things are correctly labelled and we provide an informed choice for people who purchase our products. One would argue that it's a pretty well-known standard."

Another supporter of stricter fish labelling laws is Bill Makris, owner of Melbourne's Tank Fish and Chips. Serving only fresh Australian and New Zealand fish, Makris says Tank has always insisted on including the correct name of the fish they're serving and also tries to educate their customers on where it's been caught.

"Rather than just use a generic name like flake, we'll say that it's gummy shark, or that we've got tiger flathead in today and it comes from Lakes Entrance," he said.

"There's obviously a difference in terms of price when it comes to quality and where it's from and people should know what they're eating."

Makris asserts that it doesn't make sense that a product like fish wouldn't have regulations in place across the board.

"Something's got to be done," he said. "With any other product, you get a label and the label shows where the product is made and so forth. Fishing is a primary product, it's raw, we eat it all the time. It's fine if you want to sell your customers frozen fish, just let them know it's frozen fish. Customers should know if they're eating fresh Australian fish or imported and farmed frozen fish."

At present, 70-72% of seafood consumed in Australia comes from overseas. Explains Hanlon, "Even though Australia has some fantastic local fisheries, the local industry itself can't fulfil total demand, the availability of fish isn't there. So imported seafood is an important part of our consumption profile as a country."

Concerns have been raised, however, on the conditions and practices used to produce some of these imported products. The Vietnamese basa fillets in question, for example, come from the Mekong River Basin in Indochina which has an estimated 220,000 tonnes of toxic waste dumped in it every year by large factories.

In 2007, the Australian Quarantine and Inspection Service surveyed 100 fish from the Mekong River and detected 14 antimicrobial chemicals, including "sulphonamides, tetracyclines, penicillin, quinolones, flouroquinolones and antimicrobial chemical groups", which means that antibiotics were used in the production of the fish.