Viper Fish

A viperfish is a deepwater fish with long, needle-like teeth and hinged lower jaws. It is one of the fiercest predators in the very deep part of the sea and is believed to attack its prey by luring its victim with a light producing organ called a photopore. 

Viperfish varies in color; some are green, silver or black. It uses its fang-like teeth to immobilize prey, though they are also capable to undergo long periods with scarcely any food.

Viperfish are believed to be 30-40 years in the wild, but in captivity they rarely live more than a few hours. Some species of dolphins and sharks are known to prey upon viperfish.

Source