The Terrible Pacu!

The Pacu Piranha fish! It has super strong jaws that can crush open nuts and shells.  Thankfully the massive pacu is normally a placid vegetarian. However, in some parts of the world, they have been rumored to have started taking a liking to feeding on flesh, and even biting off swimming male human genitals! OH MY!  The pacu has been given the names: "Bull-Cutter" or "Nutcracker" fish.  
CHOMP! CHOMP!

(Drawn with: Mechanical Pencil, Ball-point pen, colored pencils)