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Flatfish

Flounder

Platichthys flesus

Platichthys flesus (Linnaeus, 1758) · Pleuronectidae WoRMS 127141

Reference photos

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A dull brown to greenish-grey flatfish of estuaries and tidal rivers, and the only European flatfish that penetrates far up an estuary and lives in fresh water for long periods. Finely toothed tubercles run between the rays of the dorsal and anal fins and along the lateral line, so it feels rough where related flatfish are smooth. Many fish carry irregular reddish or orange spots on the upper side, but not as bright as a plaice's.

Depth

1 to 100 m, but usually inshore in water shallower than 50 m

Size

Up to 60 cm, commonly around 50 cm

Habitat

Mud and sand in shallow inshore water, and in estuaries and brackish water, often running on into fresh water

Behaviour

Burrows into the bottom; moves up into the intertidal with the incoming tide and feeds heavily at high tide

Diet

I eat

  • Infaunal invertebrates dug from mud and sand: bivalves such as cockles and mussels, polychaete worms and crustaceans
  • Small fishes, taken alongside the invertebrate prey once the fish is grown
  • Young fish take plankton, copepods, ostracods and small larvae before switching to larger seabed animals

Eats me

  • Seals and porpoises: grey seal, harbour seal and harbour porpoise are all recorded taking it
  • Fish-eating birds, including cormorant, grey heron and goosander
  • Young fish are heavily preyed on by brown shrimp on the nursery grounds and by comb jellies in the plankton

Where you'd find it

Found around most of Britain and Ireland, though less often in the Celtic Sea and the waters west of Ireland.

ChannelCeltic SeaNorth SeaIrish SeaW of IrelandW of Scotland
Often seenNow and thenWhere PEBL filmsBased on marine survey records (OBIS). Blank seas can mean nobody has looked there, not that the animal is absent.

Sources

Open-access references behind this page. Every statement on this page was read out of one of them; anything that could not be traced to a source was taken off the page rather than left standing. Each link was checked on the date shown, and confirmed then to be about this species.

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