From Cronaca comes the story of the parasite cymothoa exigua.

The bug...was discovered inside the mouth of a red snapper bought from a London fishmonger.

The 3.5cm creature had grabbed onto the fish's tongue and slowly ate away at it until only a stub was left.

It then latched onto the stub and became the fish's "replacement tongue".

Also worth visiting is the page linked to at the bottom of the post, which has a much more disturbing picture.