RiverFish

Bullhead · Cottus gobio

Bullhead in the River Monnow

Largest measured bullhead: 11.3 cm

The largest bullhead measured in Environment Agency surveys of the River Monnow was 11.3 cm, recorded at Llanveynoe on 9 September 2015.

Across 155 measured bullhead, the median measured length was 6.8 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 Monnow.

See bullhead records across England →

Most recent observation13 August 2025Llanveynoe
Largest measured bullhead
11.3 cm
Median length
6.8 cm
Fish measured
155
Survey locations
9

Individual EA measurements

Largest measured bullhead

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

LengthSurvey dateSurvey locationSurvey ID
11.3 cm9 Sept 2015Llanveynoe146292
10.3 cm22 Aug 2013Llanveynoe138259
10.2 cm22 Aug 2013Llanveynoe138259
10.1 cm5 Sept 2014Llanveynoe142919
9.5 cm9 Sept 2015Llanveynoe146292
9.4 cm22 Aug 2013Llanveynoe138259
9.4 cm22 Aug 2013Llanveynoe138259
9.2 cm9 Sept 2015Llanveynoe146292
9.1 cm9 Sept 2015Llanveynoe146292
9.1 cm9 Sept 2015Llanveynoe146292

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 surveyedFirst recordedLast recordedVisits finding bullhead
W05511 Jul 198913 Aug 202510
Llanveynoe13 Aug 198713 Aug 202520
Clodock11 Jul 19895 Aug 202510
W059J30 Sept 200216 Sept 20032
W059H21 Sept 200016 Sept 20033
W059G21 Sept 200016 Sept 20033
W059F22 Sept 200016 Sept 20033
W098r20 Jul 19978 Sept 19992
W098p30 Jul 19974 Sept 19992

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

1987–2025

Survey records by year

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

Fish measured by surveyors

Measured length distribution

See how the 155 measured fish were spread across different length ranges.

Smallest
2.2 cm
Lower quarter
3.9 cm
Median
6.8 cm
Upper quarter
8.1 cm
Largest
11.3 cm

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the River Monnow

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

Brown / sea trout European eel Stone loach Minnow Grayling

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 →