RiverFish

Flounder · Platichthys flesus

Flounder in the River Don

Largest measured flounder: 38.5 cm

The largest flounder measured in Environment Agency surveys of the River Don was 38.5 cm, recorded at Thorpe Marsh (Tidal) on 16 August 2017.

Across 42 measured flounder, the median measured length was 18.3 cm.

RiverFish uses Environment Agency survey measurements rather than rod-and-line angling records. These figures show fish measured during EA surveys of the River Don.

See flounder records across England →

Most recent observation4 August 2025Doncaster (crimpsal) DON/CO/TEMP/003 · 1 fish
Largest measured flounder
38.5 cm
Median length
18.3 cm
Fish measured
42
Survey locations
3

Individual EA measurements

Largest measured flounder

The largest individual measurements in this river and species dataset. Equal measurements are retained as separate surveyed fish.

LengthSurvey dateSurvey locationSurvey ID
38.5 cm16 Aug 2017Thorpe Marsh (Tidal)151314
30.5 cm4 Jul 2005Doncaster (crimpsal) DON/CO/TEMP/00387836
30.3 cm28 Jul 2011Doncaster (crimpsal) DON/CO/TEMP/003128896
28.1 cm24 Jul 2024Doncaster (crimpsal) DON/CO/TEMP/003165842
27.9 cm5 Jul 2013Doncaster (crimpsal) DON/CO/TEMP/003136984
27 cm30 Jul 2012Doncaster (crimpsal) DON/CO/TEMP/003133218
25.3 cm11 Jul 2002Doncaster (crimpsal) DON/CO/TEMP/00368780
24.7 cm25 Jul 2003Doncaster (crimpsal) DON/CO/TEMP/00378583
24.5 cm5 Jul 2013Doncaster (crimpsal) DON/CO/TEMP/003136984
23.9 cm5 Jul 2013Doncaster (crimpsal) DON/CO/TEMP/003136984

Lengths are direct survey measurements. RiverFish does not estimate fish weights from length.

Explore the river

Where flounder were found

Each point marks a survey location with at least one flounder record.

Choose a point on the map to see what was recorded there.

Map points are approximate and don’t show fishing access. Check local permissions before visiting.

Place surveyedFirst recordedLast recordedVisits finding flounder
Doncaster (crimpsal) DON/CO/TEMP/00326 Jul 20014 Aug 202515
Thorpe Marsh (Tidal)16 Aug 201716 Aug 20171
Stainforth31 Aug 199331 Aug 19931

Choose a point or table row to see the location. More survey visits can mean more records, but not necessarily more fish.

1993–2025

Survey records by year

Each bar shows how many survey visits recorded flounder that year.

Fish measured by surveyors

Measured length distribution

See how the 42 measured fish were spread across different length ranges.

Smallest
2.7 cm
Lower quarter
8.2 cm
Median
18.3 cm
Upper quarter
23.7 cm
Largest
38.5 cm

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the River Don

Compare other species with enough survey and measurement data for a detailed page.

3-spined stickleback Brown / sea trout Gudgeon Roach Minnow Perch

Before you fish

Good to know

These are past survey records, so the fish present today may be different. Map points are approximate—check local access, permissions and fishing rules before visiting.

Learn how RiverFish uses the data →