RiverFish

Bullhead · Cottus gobio

Bullhead in the River Main Allen

Largest measured bullhead: 8.8 cm

The largest bullhead measured in Environment Agency surveys of the River Main Allen was 8.8 cm, recorded at Littlewood Mill on 24 July 2017.

Across 1,274 measured bullhead, the median measured length was 5 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 Main Allen.

See bullhead records across England →

Most recent observation14 August 2025Trehannick · 53 fish
Largest measured bullhead
8.8 cm
Median length
5 cm
Fish measured
1,274
Survey locations
17

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
8.8 cm24 Jul 2017Littlewood Mill151467
8.7 cm10 Aug 2023Hillside163724
8.6 cm15 Aug 2013Trehannick137898
8.5 cm13 Jul 2011Lamellan126967
8.4 cm9 Aug 2018Treforda153011
8.3 cm13 Jul 2011Lamellan126967
8.1 cm10 Aug 2023Hillside163724
8.1 cm24 Jul 2017Littlewood Mill151467
8.1 cm15 Aug 2013Trehannick137898
8.1 cm13 Jul 2011Littlewood Mill126974

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
Trehannick25 Jul 200614 Aug 202515
Upstream Littlewood Mill10 Aug 202331 Jul 20242
Hillside10 Aug 202326 Jul 20242
Downstream Trehannick25 Jul 202319 Jul 20242
Pengenna25 Jul 202310 Jul 20242
Lamellan26 Jun 198522 Aug 202311
Littlewood Mill14 Jun 199010 Aug 202315
Treforda22 Jun 19947 Aug 202313
Dinhams Bridge19 Jun 198521 Jun 202313
Trehannick Saw Mill (control)28 Sept 201128 Sept 20111
Trehannick Saw Mill (restored)27 Sept 201127 Sept 20111
d/s Knightsmill1 Jul 198515 Sept 20036
Lanteglos15 Jun 198911 Sept 200210
Allenbrook30 May 20014 Sept 20012
Kestlewood20 Jun 198520 Jul 200010
u/s Trewen2 Jul 19902 Jul 19901
d/s Trewen10 Sept 19882 Jul 19902

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

1985–2025

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 1,274 measured fish were spread across different length ranges.

Smallest
1.6 cm
Lower quarter
3.2 cm
Median
5 cm
Upper quarter
6.2 cm
Largest
8.8 cm

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the River Main Allen

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

Brown / sea trout European eel Atlantic salmon Brook lamprey

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 →