A man described the louse he found in a fish bought from Tesco as "like something from a horror film".
Rick Beattie bought the sea bass from his local Tesco store in Belfast and was cleaning it ready to cook when the louse, similar to the one pictured above, suddenly popped out of its mouth.
Tesco has apologised and promised Mr Beattie a refund, asking him to return the product so it can begin "an urgent and thorough investigation with the supplier".
The tongue-eating louse (Cymothoa exigua) is an isopod. It's a parasite and attaches itself to the tongue of fishes such as snappers, holds on with its claws and drinks blood from the artery that lies within the tongue.
Eventually, the tongue withers away due to the reduced blood supply, but the parasite remains, turning into a replacement tongue that the fish can use as normal — in return for a share of each meal consumed.
They're not harmful to humans — but experts say they can give you a nip if you try and handle them.
One of these parasites was also found in the mouth of a snapper purchased from a fishmonger in London a few years back.
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