Grows like goliath, hunts like a tiger and swims like a fish. The Goliath Tigerfish lurks the waters of the Congo River system and several other lakes in southern Africa. This fish is remarkably adept at swimming and killing due in part to an air-filled sac in its body that allows it to detect vibrations from animals in the water. Those razorsharp spikes in its mouth may also help the cause. Growing up to 5 feet and length and weighing in at over 150 pounds, the Goliath Tigerfish makes a piranha look like a guppy in comparison to this ferocious beast. Locals say it’s the only fish that doesn’t fear the crocodile, and will even devour some of the smaller ones! In rare instances, it’s also been known to attack humans. *Gulp* As if 32 teeth the size of a Great White Shark’s weren’t scary enough, this fish has incredible eyesight in murky water and can sense low-frequency vibrations emitted by prey. It has been observed going after 60 pound catfish and literally slicing them in half.
While piranhas have a fearsome reputation and can be dangerous, piranha attacks on humans are very rare. Piranha will happily scavenge on a mortally wounded animal, though there are few if any confirmed reports of humans being killed by them. (Dogs and bees kill more people than piranha do.)
A relative of the piranha, the Megapiranha, grew to 3-feet-long (1 meter), or four times the size of today's piranhas. Scientists aren't sure why the fish-beast had seven teeth arranged in a zig-zag row, while today's piranhas sport six teeth. Fortunately the mega creature is not much of a threat, having died out several million years ago.