Tongue-eating louse, Cymothoa exigua. Attached to the tong of a Clownfish, Amphiprion ocellaris. It's a parasitic isopod that enters fish through the gills, and then attaches itself to the fish's tongue. The female attaches to the tongue and the male attaches on the gill arches beneath and behind the female. The parasite severs the blood vessels in the fish's tongue, causing the tongue to fall off. It then attaches itself to the stub of what was once its tongue and becomes the fish's new tongue. Once the parasite replaces the fish tongue begins to feed on the host's blood. Indonesia. Composite image