This is a picture of Cymothoa exigua. This parasite will eat out the tongue of its host and then act as the host’s new tongue. Once it has taken the place of the tongue, it will help its host to capture prey. Of course, it will eat a small amount of the food, but not too much.
Cymothoa exigua is considered an isopod crustacean. This group includes sowbugs and pillbugs, and has been dated back to the Carboniferous Period of the Paleozoic.
And don’t freak out, this parasite only bothers with fish. You’re safe.