RiverFish

Bleak · Alburnus alburnus

Bleak in the River Colne

Largest measured bleak: 19.4 cm

The largest bleak measured in Environment Agency surveys of the River Colne was 19.4 cm, recorded at Stanwell Moor on 13 July 2007.

Across 2,181 measured bleak, the median measured length was 9.5 cm.

Surveyors recorded weights for 79 bleak. The median was 0.3 oz (0.0079 kg) and the largest recorded weight was 2.8 oz (0.08 kg).

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

See bleak records across England →

Most recent observation4 July 2024Uxbridge · 5 fish
Largest measured bleak
19.4 cm
Median length
9.5 cm
Fish measured
2,181
Survey locations
15

Individual EA measurements

Largest measured bleak

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

LengthSurvey dateSurvey locationSurvey ID
19.4 cm13 Jul 2007Stanwell Moor106037
19 cm5 Jul 2017Springwell Lane150795
18.7 cm26 Jun 2007Springwell Lane105704
18.3 cm30 May 2012Springwell Lane132644
18.2 cm23 Jul 2003Uxbridge76533
17 cm9 Aug 2005Springwell Lane86949
16.8 cm27 Jul 2006Springwell Lane100445
16.7 cm1 Aug 2022Springwell Lane161671
16.3 cm30 May 2012Springwell Lane132644
16.2 cm27 Jul 2006Springwell Lane100445

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

Explore the river

Where bleak were found

Each point marks a survey location with at least one bleak 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 bleak
Uxbridge23 Jul 20034 Jul 202412
Stanwell Moor6 Nov 200129 Jun 202318
Springwell Lane22 Nov 200122 Jun 202320
Heathrow EP: Poyle Channel28 Oct 201928 Oct 20191
Merchant Taylors CPUE21 Sept 201521 Sept 20151
Merchant Taylor27 Jun 200721 Sept 20152
The Withey Beds20 May 201520 May 20151
u/s West Drayton Mill24 Sept 201330 Sept 20142
Merchant Taylor Backwater16 Sept 201316 Sept 20131
Denham18 Nov 200526 Jun 20123
Old Mill Lane12 Jun 198612 Jun 19861
Stanwell Road8 May 19868 May 19861
Poyle Channel7 May 19867 May 19861
Moor Roundabout4 Mar 19864 Mar 19861
Milupa Factory20 Feb 198620 Feb 19861

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

1986–2024

Survey records by year

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

Fish measured by surveyors

Measured length distribution

See how the 2,181 measured fish were spread across different length ranges.

Smallest
2.2 cm
Lower quarter
8.6 cm
Median
9.5 cm
Upper quarter
10.6 cm
Largest
19.4 cm

Lengths are direct survey measurements rather than anglers’ catches.

Fish weighed by surveyors

Measured weight summary

Recorded weights were available for 79 bleak. This is a subset of the measured fish and may not represent the whole population.

Lightest
0 oz (0.0013 kg)
Lower quarter
0.2 oz (0.005 kg)
Median
0.3 oz (0.0079 kg)
Upper quarter
0.6 oz (0.0177 kg)
Heaviest
2.8 oz (0.08 kg)

These are direct individual weights recorded by Environment Agency surveyors. Combined bulk weights are not included.

More fish in this river

Explore the River Colne

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

Chub Perch Roach Pike Dace Gudgeon

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 →