What is "fangtooth"

Fangtooths are beryciform fish of the family Anoplogastridae (sometimes spelled "Anoplogasteridae") that live in the deep sea. The name is from Greek anoplo meaning "unarmed" and gaster meaning "stomach". With a circumglobal distribution in tropical and cold-temperate waters, the family contains only two very similar species in one genus, with no known close relatives.