Sharks and piranhas are scary animals. (Of course, this means I love them on a weird level.) They have sharp teeth, can come out of nowhere and are embodiments of the awesome, deadly powers of various bodies of water (oceans and the Amazon River, respectively). Nature knows no mercy when it comes to your unarmored, fleshy body.
Imagine what it would be like if a shark and a piranha had a baby. Ditch the pack action, stick it in a river instead of an ocean, and instead of the piranha's not at all intimidating 'dinner plate' build, give it a sleek body like a torpedo. If just reading this made you wet yourself in fear, stop here and look at the cute bunny:
You may want to come back to this pic once I'm done.
Meet the offspring of the shark and piranha: The Goliath Tigerfish (Hydrocynus goliath).
The Goliath Tigerfish is the biggest fish in the genus Hydrocynus - literally, "water dog." As the name implies, these fish have killer jaws. That goes double for Goliath's - that double-hinged jaw is nasty! (Even sharks and piranhas only have one hinge to their jaws.) They are solitary predators, so there is some comfort in knowing that only one nightmare fish will come after you if you fall into the Congo.
I cannot, however, guarantee that your flesh will come out in tact.
If you are nowhere near the Congo River, you can safely avoid this fish. African humans and crocodiles are not so lucky. Goliaths have been known to tear 60-pound catfish in half, tear up young crocs on a regular basis and have a few human kills to their name - usually mistaking a finger for a fish. The Goliaths themselves can weigh upwards of 100 pounds, so young crocodiles and giant catfish are no big deal.
Yeah. Go back and look at the bunny. You will probably have a hard time not seeing it getting torn apart by those scissor-teeth.