Flounder · Platichthys flesus

Flounder in the River Stour

Largest measured flounder: 32.1 cm

The largest flounder measured in Environment Agency surveys of the River Stour was 32.1 cm, recorded at Dedham (Old) River on 15 September 1994.

Across 96 measured flounder, the median measured length was 9.8 cm.

Surveyors recorded weights for 23 flounder. The median was 0.5 oz (0.014 kg) and the largest recorded weight was 9.5 oz (0.268 kg).

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

See flounder records across England →

Most recent observation3 July 2024Downstream Dedham Mill · 1 fish

Largest measured flounder: 32.1 cm
Median length: 9.8 cm
Fish measured: 96
Survey locations: 4

Individual EA measurements

Largest measured flounder

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

Length	Survey date	Survey location	Survey ID
32.1 cm	15 Sept 1994	Dedham (Old) River	13624
24.5 cm	15 Sept 1994	Dedham (Old) River	13624
21.7 cm	30 Jun 1997	Cattawade	13667
21.6 cm	3 Jun 1985	Dedham (Old) River	13486
19.1 cm	15 Sept 1994	Dedham (Old) River	13624
18.2 cm	15 Sept 1994	Dedham (Old) River	13624
16.6 cm	24 Aug 1983	Dedham (Old) River	83022
16.5 cm	24 Aug 1983	Dedham (Old) River	83022
16.4 cm	15 Sept 1994	Dedham (Old) River	13624
16.2 cm	15 Sept 1994	Dedham (Old) River	13624

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 surveyed	First recorded	Last recorded	Visits finding flounder
Downstream Dedham Mill	23 Jun 1988	3 Jul 2024	2
Fen Bridge	26 Jul 2016	26 Jul 2016	1
Dedham (Old) River	24 Aug 1983	18 Jun 2003	8
Cattawade	4 Jun 1985	30 Jun 1997	4

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

1983–2024

Survey records by year

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

183

084

285

086

087

388

089

090

291

092

093

194

095

096

297

098

099

100

001

002

103

004

005

006

007

008

009

010

011

012

013

014

015

116

017

018

019

020

021

022

023

124

Fish measured by surveyors

Measured length distribution

See how the 96 measured fish were spread across different length ranges.

Smallest: 2.5 cm
Lower quarter: 7.4 cm
Median: 9.9 cm
Upper quarter: 12 cm
Largest: 32.1 cm

0–99 mm

100–199 mm

200–299 mm

300–399 mm

Lengths are direct survey measurements rather than anglers’ catches.

Fish weighed by surveyors

Measured weight summary

Recorded weights were available for 23 flounder. This is a subset of the measured fish and may not represent the whole population.

Lightest: 0.1 oz (0.004 kg)
Lower quarter: 0.4 oz (0.011 kg)
Median: 0.5 oz (0.014 kg)
Upper quarter: 1.8 oz (0.051 kg)
Heaviest: 9.5 oz (0.268 kg)

These are direct individual weights recorded by Environment Agency surveyors. Combined bulk weights are not included.

More fish in this river

Explore the River Stour

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

Roach European eel Perch Pike Chub Dace

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 →