Bullhead · Cottus gobio

Bullhead in the Knowl Water

Largest measured bullhead: 7.8 cm

The largest bullhead measured in Environment Agency surveys of the Knowl Water was 7.8 cm, recorded at Knowl Water Bridge (Sp) on 15 August 2019.

Across 197 measured bullhead, the median measured length was 4.9 cm.

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

See bullhead records across England →

Most recent observation17 June 2025Knowl Water Bridge (Sp) · 45 fish

Largest measured bullhead: 7.8 cm
Median length: 4.9 cm
Fish measured: 197
Survey locations: 4

Individual EA measurements

Largest measured bullhead

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
7.8 cm	15 Aug 2019	Knowl Water Bridge (Sp)	155125
7.8 cm	2 Jul 2018	Knowl Water Bridge (Sp)	152802
7.4 cm	15 Aug 2019	Mill Lane	155181
7.4 cm	2 Jul 2018	Knowl Water Bridge (Sp)	152802
7.3 cm	2 Jul 2018	Knowl Water Bridge (Sp)	152802
7.1 cm	15 Aug 2019	Mill Lane	155181
7 cm	15 Aug 2019	Footpath Ash lane	155180
6.8 cm	2 Jul 2018	Knowl Water Bridge (Sp)	152802
6.7 cm	15 Aug 2019	Mill Lane	155181
6.7 cm	15 Aug 2019	Knowl Water Bridge (Sp)	155125

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

Explore the river

Where bullhead were found

Each point marks a survey location with at least one bullhead 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 bullhead
Knowl Water Bridge (Sp)	10 Sept 1996	17 Jun 2025	7
Mill Lane	15 Aug 2019	15 Aug 2019	1
Footpath Ash lane	15 Aug 2019	15 Aug 2019	1
Wrafton (Sp)*	30 Aug 1996	17 Sept 1999	2

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

1996–2025

Survey records by year

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

296

097

098

299

000

001

002

003

004

105

006

007

008

009

010

011

112

013

014

015

016

017

118

319

020

021

022

023

024

125

Fish measured by surveyors

Measured length distribution

See how the 197 measured fish were spread across different length ranges.

Smallest: 2.3 cm
Lower quarter: 3.4 cm
Median: 4.9 cm
Upper quarter: 5.9 cm
Largest: 7.8 cm

0–99 mm

197

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the Knowl Water

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

Brown / sea trout European eel

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 →