Viperfish can grow up to 25 inches long and have large mouths with long teeth. They are preyed upon by humans, sharks, dolphins and dragonfish. Viperfish can live for 15 to 40 years. Humans hunt viperfish because they are predators. Viperfish feed mostly on crustaceans and are found at depths from 500 to 2500 meters during the day, swimming to shallower waters at night to find more food.