Waryfishes are deep-sea aulopiform fishes in the small family Notosudidae. They are thought to have a circumglobal distribution in sub-Arctic to subantarctic waters. The family name "Notosudidae" derives from the Greek noton (back) and Latin sudis (a fish, esox, the name of salmon).
Waryfishes are slender, scaled, fish, similar in appearance to lancetfishes, but lacking the greatly enlarged dorsal fin. Although the adults are deep water fish, the larvae inhabit surface waters, and are unique in having teeth on the upper jaws. Waryfishes lack a swim bladder.