Flounder · Platichthys flesus

Flounder in the River Yarrow

Largest measured flounder: 23.5 cm

The largest flounder measured in Environment Agency surveys of the River Yarrow was 23.5 cm, recorded at Below Croston Weir on 4 July 2011.

Across 57 measured flounder, the median measured length was 16.2 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 Yarrow.

See flounder records across England →

Most recent observation5 July 2023Below Croston Weir · 6 fish

Largest measured flounder: 23.5 cm
Median length: 16.2 cm
Fish measured: 57
Survey locations: 2

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
23.5 cm	4 Jul 2011	Below Croston Weir	126926
23.1 cm	4 Jul 2011	Below Croston Weir	126926
23 cm	4 Jul 2011	Below Croston Weir	126926
22.7 cm	4 Jul 2011	Below Croston Weir	126926
22 cm	4 Jul 2011	Below Croston Weir	126926
20.9 cm	4 Jul 2011	Below Croston Weir	126926
20.8 cm	4 Jul 2011	Below Croston Weir	126926
20.7 cm	4 Jul 2011	Below Croston Weir	126926
20.6 cm	4 Jul 2011	Below Croston Weir	126926
20.4 cm	4 Jul 2011	Below Croston Weir	126926

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
Below Croston Weir	26 Jun 2001	5 Jul 2023	5
Downstream Croston STW	5 Jul 1995	5 Jul 1995	1

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

1995–2023

Survey records by year

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

195

096

097

098

099

000

101

002

003

104

105

006

007

008

009

010

111

012

013

014

015

016

017

018

019

020

021

022

123

Fish measured by surveyors

Measured length distribution

See how the 57 measured fish were spread across different length ranges.

Smallest: 7.4 cm
Lower quarter: 13.9 cm
Median: 16.2 cm
Upper quarter: 19.4 cm
Largest: 23.5 cm

0–99 mm

100–199 mm

200–299 mm

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the River Yarrow

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

Brown / sea trout European eel Chub Gudgeon Perch 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 →