RiverFish

Stone loach · Barbatula barbatula

Stone loach in the River Colne

Largest measured stone loach: 9.3 cm

The largest stone loach measured in Environment Agency surveys of the River Colne was 9.3 cm, recorded at Watford M1 link road on 21 July 2004.

Across 10 measured stone loach, the median measured length was 7.9 cm.

Surveyors recorded one individual weight: 0.2 oz (0.0062 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 stone loach records across England →

Most recent observation16 July 2026Watford M1 link road
Largest measured stone loach
9.3 cm
Median length
7.9 cm
Fish measured
10
Survey locations
11

Individual EA measurements

Largest measured stone loach

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

LengthSurvey dateSurvey locationSurvey ID
9.3 cm21 Jul 2004Watford M1 link road80609
9.2 cm10 Jul 2003Watford M1 link road76370
8.3 cm21 Jul 2004Watford M1 link road80609
8 cm21 Jul 2004Watford M1 link road80609
8 cm11 Feb 1986Springwell Lane115940
7.8 cm10 Jul 2003Watford M1 link road76370
7.6 cm21 Jul 2004Watford M1 link road80609
7.4 cm10 Jul 2003Watford M1 link road76370
6.8 cm22 Jul 2005Watford M1 link road85168
3.7 cm7 Jul 2015Watford M1 link road145318

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

Explore the river

Where stone loach were found

Each point marks a survey location with at least one stone loach 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 stone loach
Watford M1 link road10 Jul 200316 Jul 202612
Wall Hall26 Jun 200814 May 202612
Uxbridge11 Jun 200724 Jul 20257
Stanwell Moor21 May 202421 May 20241
Springwell Lane11 Feb 198622 Jun 20237
Drop Lane27 May 201523 May 20232
Watford Tesco Extra26 Jul 202226 Jul 20221
Lairage Land26 Jul 202226 Jul 20221
Heathrow EP: Little Britain31 Oct 201931 Oct 20191
Denham3 Aug 201016 Jul 20152
Cowley, Old Mill Lane19 May 200919 May 20091

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

1986–2026

Survey records by year

Each bar shows how many survey visits recorded stone loach that year.

Fish measured by surveyors

Measured length distribution

See how the 10 measured fish were spread across different length ranges.

Smallest
3.7 cm
Lower quarter
7.5 cm
Median
7.9 cm
Upper quarter
8.2 cm
Largest
9.3 cm

Lengths are direct survey measurements rather than anglers’ catches.

Fish weighed by surveyors

Measured weight summary

One individual weight was recorded for this fish and river. This is a subset of the measured fish and may not represent the whole population.

Recorded weight
0.2 oz (0.0062 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 →