English: 1=Model of a North Atlantic longnose lancetfish (Alepisaurus ferox) at the Sant Hall of Oceans at the Smithsonian Museum of Natural History in Washington, D.C., USA. Lancetfish grow to be about 6.6 feet (2 m) in length. Very little is known about them, even though they are quite common throughout the worlds oceans (except for the polar regions). Lancetfish are predatory, ambushing plankton, squid, and other fish. Sharks, albacore and yellowfin tuna, and seals all are known to eat lancetfish.