This is the tongue-eating louse. This parasitic crustacean latches onto the tongue of its primary victim, the spotted rose snapper, and doesn’t let go. Once it does, the louse sucks the blood out of the tongue, until the organ wastes away. When that happens, the louse essentially becomes the new tongue, attaching its body to the stub of the old organ. It then feeds on the remains of food that the snapper doesn’t completely swallow.
Amazingly, the snapper isn’t harmed too much by the entire process as it continues to live and feed after the louse makes a permanent residence. Though the spotted rose snapper is the louse’s main target, the crustacean has been found sporadically in several other species.
Is it weird that, for me, the worst thing about this is that the fish has kind of human looking teeth?