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up to 70 centimeters


up to 3 kilograms


gray-brown on the right side, creamy white on the left side


20 years


worms, shellfish, crustaceans


swimming, burrowing


people, seals, zeehonden



  • Dut: Tong, gewone tong
  • Lat: Solea solea
  • Eng: Sole (common sole)
  • Ger: Seezunge
  • Fren: Sole (sole commune)
  • Dan: Tunge
Sole, Ecomare


Sole has a flattened elongated body. It can burrow itself almost completely in a sandy or muddy bottom, where it mostly lives. Just like most other flatfish species, both eyes are located on the right side of the body. It looks for worms using feelers hanging under its chin. Sole is a nocturnal hunter. At night, this species sometimes swims far above the sea floor where the sea current carries it to other territories. When it comes time to spawn, it migrates to the same grounds in the southern North Sea every year.

  • Advantage from fisheries?

    Sole is the most important fish for Dutch fishermen. They earn them lots of money because it is such a tasty fish. Strange enough, this fish profits from beam trawl fisheries. When the heavy chains churn up the sea bottom, many benthic animals are killed or wounded. This forms easy prey for sole and other bottom scrapers such as crabs and starfish. Furthermore a sole's favorite food, worms, grows well in the churned-up sea floor.

  • Distribution
    Distribution of sole, Ecomare

    Sole is a common fish species found in the northeastern section of the Atlantic Ocean and in the North Sea. It has a preference for warm sea bottoms. The North Sea is the northern border for its distribution area. During severe winters, sole migrates to places where the sea floor remains the warmest. According to studies done by fishery biologists from ICES, this species is spreading its distribution area further northwards. The Wadden Sea is one of the important nursery areas for young sole.

  • Development of the sole stock
    Spawning stock and yield of plaice (North Sea), Ecomare

    In 2015, 40 thousand tons of sole swam in the North Sea. That is much more than a few years ago which is why fishery biologists believe that sole is out of the danger zone. Experience from the past shows that it's not smart to raise the catch allowances immediately, since the sole stock in the North Sea is known to fluctuate strongly. The fishery pressure on the sole stock in the North Sea has decreased since the 1990s, partially due to the reduction in the fishery fleet, and has been reasonably stable in the past ten years.

  • Strange-looking sole
    Tong met dubbel achterlijf (© Jan Hendrik Romkes)
    Sole with a double rear end, Jan Hendrik Romkes

    Sometimes, fishermen catch strange-looking sole in the North Sea. In 2013, the cutter TX14 caught a number of sole in the southern North Sea with large blisters on their body. According to researchers from IMARES, the blisters were caused by the cold seawater temperatures. "These blisters are a kind of frostbite and are caused by prolonged exposure to a water temperature below 5°C. Damaged skin and a reduced resistance cause ulcer formation," according to one of the researchers. Jan Hendrik Romkes from the cutter BCK40 caught a sole with a double hind body. A second rear end appeared from the hind end of the front part of the double sole. This strange shape is a growth disorder which probably developed in the egg stage. It looks like a kind of Siamese twin sole.

  • Farming sole

    It is very difficult to farm sole, but the company Solea in IJmuiden has succeeded. A project was started in Zeeland, called the 'Zeeuws Tong', whereby sole is farmed in troughs.