Stefano Mariani Finds 3 of 10 Samples Sold Cat Fish
DNA tests found cat fish sold as fish and chips in three of 10 sampled chip shops in Liverpool and Manchester. Professor Stefano Mariani, who oversaw the testing, said the samples identified pangasius in three takeaways.
The finding leaves customers with a specific problem: fish bought as traditional fish and chips was not always what the menu implied. One Liverpool chip shop owner complained to the about the practice, saying: "This goes on more than you'd think and it's putting people like me at a disadvantage,"
Mariani's DNA test
Mariani said Liverpool John Moores University used DNA barcoding to identify the species. He said, "We used DNA barcoding to identify the species, and we found three out of the 10 samples were pangasius - often known as river cobbler on the market, a type of tropical freshwater catfish."
He added, "In my experience with fish and chips, three out of 10 is quite a lot - I don't recall seeing this level of catfish."
Liverpool and Manchester sample
The identified 10 businesses for a sample test, with five in Liverpool and five in Manchester. Three of the chip shops listed cod on the menu, four listed haddock and three listed just fish. The three businesses that did not list a species told the they were normal fish or white fish.
In one case, the server gestured to a sign that said traditional fish and chips. The investigation also found online reviews from customers saying they had not a clue what type of fish they bought, or that it was not cod or haddock.
Fish price gap
Pangasius is often known on the market as river cobbler and is a type of tropical freshwater catfish. It is described as safe to eat and costs about £3.40 per kilogram wholesale, compared with about £15 per kilogram for traditional species such as cod and haddock.
The Chartered Trading Standards Institute said mis-selling or misdescription of fish was not a widespread issue, but said some unscrupulous businesses still existed. Under the rules described in the investigation, a business is legally obliged to tell a customer the species if asked.
For customers in Liverpool and Manchester, the practical takeaway is narrow but direct: if a chip shop will not name the species, asking before ordering is the only step the investigation itself shows is available, and the DNA result shows why that question is not merely cosmetic.
