RiverFish

Brown / sea trout · Salmo trutta

Brown / sea trout in the River Mimram

Largest measured brown / sea trout: 56.1 cm

The largest brown / sea trout measured in Environment Agency surveys of the River Mimram was 56.1 cm, recorded at Codicote restoration u/s on 6 October 2012.

Across 2,308 measured brown / sea trout, the median measured length was 16.5 cm.

Surveyors recorded weights for 31 brown / sea trout. The median was 5.6 oz (0.16 kg) and the largest recorded weight was 1 lb 9.4 oz (0.72 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 Mimram.

See brown / sea trout records across England →

Most recent observation7 May 2026Chandlers End, Mill Farm · 5 fish
Largest measured brown / sea trout
56.1 cm
Median length
16.5 cm
Fish measured
2,308
Survey locations
27

Individual EA measurements

Largest measured brown / sea trout

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

LengthSurvey dateSurvey locationSurvey ID
56.1 cm6 Oct 2012Codicote restoration u/s134643
53.8 cm23 Sept 2019Tewin Archers155725
52.6 cm16 Oct 2018Tewin Archers153874
52.5 cm17 May 2023Chandlers End, Mill Farm163190
52.3 cm7 Oct 2014Tewin Flyfishers143371
52.2 cm5 Apr 2007Tewin Flyfishers105158
52 cm7 May 2026Chandlers End, Mill Farm182135
51.8 cm23 Sept 2019Tewin flyfishers middle155724
51.8 cm6 Nov 2013Panshanger quarry139989
51.5 cm17 May 2023Chandlers End, Mill Farm163190

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

Explore the river

Where brown / sea trout were found

Each point marks a survey location with at least one brown / sea trout 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 brown / sea trout
Chandlers End, Mill Farm1 May 20147 May 20264
Tewin Flyfishers5 Apr 200725 Sept 202518
Panshanger quarry15 Jun 20062 Sept 202518
Upstream Tewin Fly Fishers3 Oct 20233 Oct 20242
Singlers Marsh8 Oct 201426 Sept 20242
Codicote restoration middle fully quant15 Oct 201426 Sept 20242
Duck Trap Wood10 May 200630 Aug 20245
Rose Farm13 Jul 200628 Aug 20243
Sherrardswood School12 Jul 20175 Apr 20235
Fulling Mill12 Jul 20174 Apr 20235
Codicote Station 111 Jul 20174 Apr 20235
Welwyn Allotments11 Aug 202111 Aug 20211
Welwyn High Street10 Aug 202110 Aug 20211
Tewin flyfishers middle8 Oct 201523 Sept 20194
Tewin Archers8 Oct 201523 Sept 20194
Codicote Station 211 Jul 20176 Feb 20193
Tewin Water House Investigation3 Oct 20183 Oct 20181
Codicote restoration u/s6 Oct 20126 Oct 20121
Panshanger quarry broadwater bypass channel22 Oct 201021 Sept 20112
Rye end cottages12 Jul 200626 Feb 20072
Upstream Panshanger weir16 Jun 200616 Jun 20061
Codicote bottom farm14 Jun 200614 Jun 20061
u/s Tewin Bury farm13 Jun 200613 Jun 20061
School/corn mill13 Jun 200613 Jun 20061
Nanny Ford16 May 200616 May 20061
Tewin Bury Farm19 Nov 200319 Nov 20031
Cole Green Way Farm14 Oct 200314 Oct 20031

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

2003–2026

Survey records by year

Each bar shows how many survey visits recorded brown / sea trout that year.

Fish measured by surveyors

Measured length distribution

See how the 2,308 measured fish were spread across different length ranges.

Smallest
4.2 cm
Lower quarter
10.7 cm
Median
16.5 cm
Upper quarter
23.3 cm
Largest
56.1 cm

Lengths are direct survey measurements rather than anglers’ catches.

Fish weighed by surveyors

Measured weight summary

Recorded weights were available for 31 brown / sea trout. This is a subset of the measured fish and may not represent the whole population.

Lightest
0.2 oz (0.006 kg)
Lower quarter
1.3 oz (0.037 kg)
Median
5.6 oz (0.16 kg)
Upper quarter
10.6 oz (0.3 kg)
Heaviest
1 lb 9.4 oz (0.72 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 Mimram

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

Bullhead Stone loach 3-spined stickleback Minnow 10-spined stickleback 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 →