What Species of Fish Are You Really Eating?

In early 2013 it became apparent that many beef products sold around the UK in supermarkets, shops and restaurants actually contained horsemeat. The scale of this scandal soon became apparent and almost all of the major supermarket chains and were implicated, and meat products sent to schools, hospitals and prisons was also mislabelled, leading to the public becoming aware of the complicated and untraceable origins of meat products which end up on sale in the in the UK (1). Indeed, it soon emerged that the scale of the scandal meant that it was clear that this was no simple labelling mistake but an industrial scale fraud motivated by the fact that horsemeat costs significantly less than beef. Despite this, fish products appear to have escape attention with many consumers still confident that the fish they purchased was accurately labelled.

Fish 'n' Chips
Fish and chips is one of the nation’s favourite dishes – but the cod or haddock people think they are buying may actually be a different species of fish altogether.

Commonly Mislabelled Species

However, in April 2013 news broke that a study by the University of Salford which stated that up to 7% of the fish sold in the UK was mislabelled (2). Studies from elsewhere in the world have found similar issues, with research in the Republic of Ireland indicating that up to 25% of the fish on sale there was incorrectly identified (3), and an American study found that on average 33% of fish was mislabelled, and in some areas the proportion was much higher (4).

A report on BBC Radio 4’s today programme on 2nd April 2013 stated that the most common mislabelling involved passing off pollock or coalfish (referred to as saithe in the programme) as cod – a practice that is a worthwhile endeavour for those doing the mislabelling as cod can command prices almost double that of pollock or coalfish. However, it was also stated that a species of fish known as basa was also labelled as cod. Basa, also known as Vietnamese river cobbler (or Pangasius bocourti to give it its scientific name), is a species of fish native to Vietnam and Thailand. It is sold worldwide and is often raised in vast farms in river estuaries. Like cod it produces white, flaky flesh once it has been cooked, but fetches a much lower price than prime cod in the UK market.

As well as species being mislabelled there are also issues with the place of origin of species sold in the UK – in November 2013 Sainsbury’s supermarket were forced to apologise after selling jellied eels as being British when they actually came from New Zealand. In 2017 the Food Standards Agency (FSA) warned that fish sold in restaurants was regularly being mis-sold as a more expensive species to boost profits. The FSA warned that regulations were so weak that rogue restaurants could easily get away with the crime, and once fish had been filleted it required DNA testing to accurately identify the species, making detecting mislabelling extremely difficult. The problem is not limited to the UK. In 2021 the New York Times commissioned laboratory tests on tuna sandwiches sold at three Subway sandwich shops in Los Angles. Researchers were unable to find any tuna DNA in the sandwiches, either because a different species was used or the tuna had been so heavily processed that the DNA could not be located. Subway strongly maintain that their sandwiches do contain the ingredients listed.

Basa Fish
Basa fish, also known as Vietnamese river cobbler, is sometimes passed off as cod.

While fresh fish on the wet fish counter of supermarkets and fishmongers may be caught in UK waters by fishermen working out of British ports and harbours much of the fish which is used in frozen products is sourced from Asia. China is the world’s biggest fish processor and much of the fish that comes into the UK is caught in China and frozen before being flown into Frankfurt airport in Germany where it is distributed throughout Europe by road. As the fish are already filleted and frozen when they arrive in Europe it is easy for the mislabelling to take place somewhere along the line, with DNA testing required to truly establish the species of the fish. Dr. Stefano Mariani, one of the authors of the University of Salford study told the BBC:

“We known that there are some suppliers that were consistently handling fish which was proven to be mislabelled, which suggests that a lot of mislabelling occurs before it gets delivered to the supermarkets” (5).

Additional test carried out in Germany by Eurofins, an international organisation which conducts research into pharmaceutical, biological and environmental issues also found high levels of mislabelled fish. Eurofin’s director of scientific research, Dr. Bert Popping, said:

“The authorities at the airport at Frankfurt have also found some new species … fish species which have not previously entered the food chain, [species] that have not previously been commercialised” (5).

Caviar may have been mislabelled.

It is not only commonly bought and sold fish and fish products which are mislabelled. In May 2013 reports emerged that King’s Fine Foods, a company which supplies both Harrods of London and Fortnum & Mason (who are the official Grocer to the Queen), were under investigation by Richmond Council for allegedly selling mislabelled caviar. Random DNA tests had supposedly revealed that some of the caviar supplied by the company which was supposedly from the stellate sturgeon (Acipenser stellatus) were actually from the small sturgeon species commonly known as sterlet (Acipenser ruthenus). The price difference of caviar made from the the two species is vast, with stellate sturgeon caviar selling for up to £1300 per kilogram, but sterlet sturgeon caviar fetching much lower prices. King’s Fine Foods were reported to have removed all potentially incorrectly labelled products from sale and sent all of their other caviar products for DNA testing to check exactly which species of sturgeon it came from (6).

What Can Be Done?

Eurofins Scientific Logo
Eurofins is a scientific organisation which has carried out research into the species of fish sold throughout Europe.

Unfortunately the supply chains for fish coming to the UK are so complex and convoluted that it is extremely difficult to confirm the species of fish that have been imported into the UK. Mark Drummon, the Vice President of the Federation of Fish Friers (a trade body for fish and chip shop owners) told the BBC that fish caught by factory trawlers in European waters were the safest choice as they were frozen within an hour and a half of being caught and the labelling criteria was much stricter and more accurate than fish coming from China. This may be correct by as stated in the article on commercial fishing this type of industrial fishing is extremely damaging to the marine environment and large scale industrial factory trawlers are one of the reasons Europe’s fish stocks are in so depleted.

In reality the only way to be absolutely sure of the fish species which is being consumed is by purchasing the fish whole from a fishmongers or wet fish counter – there is always the risk that pre-packaged, filleted or frozen fish may not the the species stated on the label or packet. However, the horsemeat scandal has raised awareness of the issues around labelling animal products, and hopefully the on-going controversy over this issue will carry over to fish products, and UK consumers will have a more accurate and truthful picture of the species of fish they are actually buying.


  1. Lawrence, F. Horsemeat Scandal Timeline – The Guardian, 10 May 2013.
  2. News Agencies, Seven per Cent of Fish Solf in Britain Mislabelled – The Telegraph, 2 April 2013.
  3. Study Finds 25% of Fish on Sale are Mislabelled – European Commisson: Cordis (Community Research and Development Information Service)
  4. Clark Howard, B. New Oceana Study Finds 33% of Seafood Mislabelled National Geographic, Ocean Views, 21 February, 2013.
  5. Today Programme, BBC Radio 4, 2 April 2013.
  6. Daily Mail Reporter, Caviar Supplier Investigated After Mislabelling Cheap Products as Top Grade Which Was Supplied to the Queen’s Grocer – The Daily Mail, 20 May 2013.