Staff at a Waitrose fish counter refused to fillet a trout for a customer because it was "too slippery".
In the example of bizarrely excessive red tape, the customer complained to the Health and Safety Executive and Waitrose has since apologised.
According to the Telegraph, the fishy incident follows that of another Waitrose customer who complained that a butcher at a different store had refused to bone a leg of lamb for him. Londoner Stuart Rock said the butcher had said he was able to do the job, but was not allowed due to health and safety.
On its website, Waitrose states: "Waitrose has fish specialists in most of its branches who can advise on what fish to buy. Waitrose fish specialists are trained at London's Billingsgate Seafood Training School.
"Not only can they gut, clean and fillet fish, they also know how to cook every variety they stock."
When the unnamed customer approached the fish counter, an assistant agreed to fillet a whole trout but a supervisor stepped in to say it would not be possible on health and safety ground because the fish were too slippery, the HSE reported.
The HSE, which has a panel to investigate health and safety myths, said it was an example of "poor customer service hiding behind the health and safety excuse".
It added: "Slippery fish are a fact of life."
"Whilst fish filleting requires the person to know how to us knives safely, it is reasonable to expect this service to be available at a fishmonger's counter in a supermarket especially when the website advertises the service."
Judith Hackitt, chair of the Health and Safety Executive, said: "I'm glad the customer didn't fall for this red herring.
"This is just another case of poor customer service and nothing to do with health and safety."
Waitrose apologised for any inconvenience for both incidents.
Health and safety gone mad
In 2012 the HSE launched the Myth Busters Challenge Panel to encourage consumers to report incidents of extreme health and safety rules.
Common examples of needlessly excessive health and safety rules include cafés and restaurants refusing to warm up baby food for mothers; golfers being told they cannot ride in buggies on a golf course and office workers being told that they cannot wear open-toe sandals.
More bizarre decisions made on health and safety grounds included a school pointlessly relocating a tree house outside of school grounds, and people being banned from sleeping in a camper van on a campsite.