A local found a creepy tongue-eating louse in his grilled fish.

Koson Sae Tae, 51, bought mackerel from the market to share with his family for lunch in Phetchabun province, Thailand, on January 19.

However, Koson discovered the tiny creature squeezed inside the fish's head and pulled it out to reveal the parasitic isopod.

Footage shows a tongue-eating louse, already dead inside the grilled fish, when Koson found it, being held by the man as he inspected what it was.

He said: ‘I will not eat grilled mackerel for a while. It tasted good, but I lost my appetite when I saw and found out what had been hiding inside its head.'

The tongue-eating louse, scientifically known as Cymothoa exigua, enter the fish through its gills. Within the fish's mouth, they become male and attach themselves to the fish's gills. Eventually, one louse transforms into a much larger female, leaving the males to shrink and become her mate. The female then latches onto the fish's tongue with hooked mouthparts and injects digestive enzymes, essentially severing the blood supply to the tongue.