A retired headmaster said he has been put off fish for life after discovering a vile flesh-eating louse in a sea bass bought from Morrisons.

Paul Poli was about to tuck into his supper when he spotted the yellow parasitic crustacean on the fish, reports the Daily Mirror.

According to the newspaper, the 62-year-old from Swansea, South Wales was told the bug was cymothoa exigua when he returned the sea bass to his local Morrisons branch.

The parasite – commonly known as the tongue-eating louse – feeds itself by eating a fish’s tongue, attaching itself to the stub and acting as a tongue for the fish – taking some of the food for itself.

Tongue-eating parasite discovered in supermarket fish

"It was disgusting - I love fish but it's put me off it for life now,” Poli told the Mirror.

"It was about 3cm long and 8mm wide - luckily just big enough for me to see it before I put it in my mouth."

The supermarket apologised to Poli with a bottle of wine and £20 voucher.

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A spokesman said: "Some fish often pick up parasites naturally from their eco system.

"Although we make every effort to screen these out during the skinning or packaging processes, they may be present on very rare occasions.

"Our skilled fishmongers will also identify them as they fillet a fish - Mr Poli's fish was sold un-filleted at his request."

Although ugly, cymothoa exigua are not harmful to humans but they can bite when alive.