Halibut is a flatfish, genus Hippoglossus, from the family of the right-eye flounders (Pleuronectidae). Other flatfish are also called halibut. The name is derived from haly (holy) and butt (flat fish), for its popularity on Catholic holy days. Halibut are demersal fish which live in the North Pacific and the North Atlantic oceans. They are highly regarded food fish.