The Atlantic halibut is among the largest of bony fishes in the world with a maximum recorded size of 4.7 m. The largest in Icelandic water measured 3.56 m. Common size in catches is 30-150 cm.
It is found over most of the North Atlantic and a close relative, the Pacific halibut (Hippoglossus stenolepis) is to be found in the North Pacific. The distribution range is very similar as for Atlantic and Pacific cod.
The halibut spawns in very deep waters at around 2000 m depth in February to April. Around the age of one year, the juveniles appear in shallow waters, where they stay for about two years. They gradually move deeper, and at the age of 9 to 10 they join the adults, which spend most of their time in deep waters. The Atlantic halibut matures around the age of 7 to 14, the males earlier than females. As are most flatfishes, the Atlantic halibut is a benthic fish usually found on a sandy or muddy bottom. It migrates widely over a considerable depth range as mentioned before. It is a voracious feeder, eating whatever it can handle, and mostly other fishes.
The halibut occurs all around Iceland but is more common in the warmer waters to the south and west of the country. It has probably been fished in Icelandic waters since people settled there, but not in any high numbers before the 20th century. The halibut is one of the most popular fishes for consumption in Iceland. It has been a very welcome bycatch in other fisheries throughout the centuries.