In many ways, this jawless fish does not look like a fish. It does not have fins on its sides or scales.  It does have a round mouth filled with more than a hundred teeth.  It uses its sharp teeth and round mouth well.  As a parasite, it feeds off of the blood and body fluids of other fish.  Using its round mouth like a suction cup, it attaches itself to a body of a fish.  It uses its teeth and its file-like tongue to take away a hole in the fish to get out the blood and other fluids.  Once attached, it stays with the fish.  Sometimes for days until the fish finally dies.