European Flounder Identification Guide

Key identification features

• Right-eyed, oval to rounded flatfish body
• Row of small bony tubercles (knobs) along the base of the dorsal fin, anal fin, and lateral line
• Dull olive-brown to greyish-brown upper side, sometimes with faint, dull orange blotches
• Pale, sometimes speckled, white underside
• Lateral line only slightly curved above the pectoral fin
• Typically 20-40 cm, with a somewhat rough feel along the fin margins

Common look-alikes

• European plaice – has bright, well-defined orange-red spots and smooth skin, lacking the bony tubercles.
• Common dab – shows a much more strongly curved lateral line and overall rougher, sandpapery scales.
• Turbot – left-eyed, not right-eyed, and far more rounded and scaleless.

Where you'll see one

European flounder are found along coastal waters, estuaries, and river mouths throughout Europe, from the Baltic and White Sea south to the Mediterranean. Unusually for a marine flatfish, they readily tolerate brackish and even fresh water, regularly moving far upstream into rivers and lakes well beyond the reach of the tide.