Flounder · Platichthys flesus

Flounder in the River Alt

Largest measured flounder: 20.1 cm

The largest flounder measured in Environment Agency surveys of the River Alt was 20.1 cm, recorded at Alt Weir Downstream on 1 May 2026.

Across 15 measured flounder, the median measured length was 10 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 Alt.

See flounder records across England →

Most recent observation1 May 2026Alt Weir Downstream · 1 fish

Largest measured flounder: 20.1 cm
Median length: 10 cm
Fish measured: 15
Survey locations: 6

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
20.1 cm	1 May 2026	Alt Weir Downstream	181192
20 cm	17 Jul 2001	Alt Bridge	90496
19.9 cm	18 Oct 2007	Bull Bridge	108830
11.5 cm	4 Sept 1996	Carr Houses	114733
11 cm	4 Sept 1996	Carr Houses	114733
11 cm	4 Sept 1996	Carr Houses	114733
10 cm	4 Sept 1996	Carr Houses	114733
10 cm	4 Sept 1996	Carr Houses	114733
9.5 cm	18 Oct 2007	Bull Bridge	108830
9.5 cm	4 Sept 1996	Carr Houses	114733

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
Alt Weir Downstream	1 May 2026	1 May 2026	1
Bull Bridge	31 Aug 2005	18 Oct 2007	2
Alt Bridge	17 Jul 2001	17 Jul 2001	1
Carr Houses	4 Sept 1996	4 Sept 1996	1
Carr Side Farm	3 Sept 1996	3 Sept 1996	1
Homer Green	2 Sept 1996	2 Sept 1996	1

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

1996–2026

Survey records by year

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

396

097

098

099

000

101

002

003

004

105

006

107

008

009

010

011

012

013

014

015

016

017

018

019

020

021

022

023

024

025

126

Fish measured by surveyors

Measured length distribution

See how the 15 measured fish were spread across different length ranges.

Smallest: 6 cm
Lower quarter: 9.1 cm
Median: 10 cm
Upper quarter: 11.3 cm
Largest: 20.1 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 Alt

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

Gudgeon Chub European eel Roach Pike

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 →