Hippoglossus hippoglossus, (the Danish name comes from “holy flounder”) is the undisputed largest of all flatfish. The fish live in the North Atlantic from Newfoundland across Greenland, the North Atlantic islands, northern Scandinavia, and to the Biscay. The fish is right-turned and can grow over 2 meters long and weigh up to 300 kilos. As it prefers very cold water, it is most often found at great depths in Denmark, e.g. The Norwegian channel in the Skagerrak, but it is also known from the North Sea and Kattegat.

In addition to the halibut species in the Atlantic Ocean, there is a close relative in the North Pacific that can grow almost as large: the Hippoglossus stenolepis.