Direct individual measurements
Largest grass carp by waterway
Ranked by the largest individual measured in EA surveys. The sample size shows how many valid length measurements underpin each waterway's figures.
| Rank | River or waterway | Largest | Median | Measured | Measured at |
|---|---|---|---|---|---|
| 1 | Silver Springs LakesSouth West | 79.2 cm (31.2 in) | 79.2 cm (31.2 in) | 1 | 23 Nov 2017Coarse Lake |
| 2 | River StillwatersMidlands | 68 cm (26.8 in) | 60.4 cm (23.8 in) | 2 | 11 Dec 2014Heatherton |
| 3 | Lincolnshire LakesAnglian | 67.4 cm (26.5 in) | 37.5 cm (14.8 in) | 218 | 5 Feb 1998Alvingham Fisheries |
| 4 | Lee NavigationSouth East | 66.3 cm (26.1 in) | 66.3 cm (26.1 in) | 1 | 8 Jul 2025Hertford Basin |
| 5 | River Molesey - TeddingtonSouth East | 58.5 cm (23 in) | 55.2 cm (21.7 in) | 2 | 15 Sept 2004Molesey - Thames Ditton Island, Upper Main Channel |
| 6 | Louth CanalAnglian | 41.5 cm (16.3 in) | 41.5 cm (16.3 in) | 1 | 13 May 2010Tetney Lock |
Equal maximum lengths are ordered by sample size. Measurements are shown as recorded and are not converted into estimated weights.
225 fish measured
Measured grass carp lengths
The median divides the measured sample in half. This distribution describes surveyed fish, not every grass carp living in England.
Only positive individual lengths that pass RiverFish's general measurement checks are included. Each bar covers a 20 mm range.
Latest EA evidence
Latest grass carp observations
The ten most recent survey visits that recorded grass carp in named waterways.
| Date | River or waterway | Survey location | Fish recorded |
|---|---|---|---|
| 8 Jul 2025 | Lee Navigation | Hertford Basin | 1 |
| 16 Sept 2019 | River Molesey - Teddington | Molesey - Thames Ditton Island, Upper Main Channel | 1 |
| 23 Nov 2017 | Silver Springs Lakes | Coarse Lake | 1 |
| 11 Dec 2014 | River Stillwaters | Heatherton | 2 |
| 13 May 2010 | Louth Canal | Tetney Lock | 1 |
| 25 Feb 2009 | River Manchester | Reddish Vale Bottom Pool, Stockport | 1 |
| 23 Nov 2005 | Lincolnshire Lakes | Wagtail Lodge (Specimen Lake) | 1 |
| 2 Nov 2004 | Lincolnshire Lakes | Wagtail Lodge (Island Lake) | 2 |
| 15 Sept 2004 | River Molesey - Teddington | Molesey - Thames Ditton Island, Upper Main Channel | 1 |
| 12 Dec 2002 | Lincolnshire Lakes | Bullrushes Tetney | 1 |
A survey record confirms grass carp at that place and time. It does not show present-day abundance or fishing access.
19 positive survey visits
Survey distribution
EA surveys recorded grass carp at 17 locations across 7 named waterways represented on RiverFish.
| Region | Waterways | Locations | Survey visits | Latest record |
|---|---|---|---|---|
| Anglian | 2 | 12 | 13 | 13 May 2010 |
| South East | 2 | 2 | 3 | 8 Jul 2025 |
| Midlands | 1 | 1 | 1 | 11 Dec 2014 |
| North West | 1 | 1 | 1 | 25 Feb 2009 |
| South West | 1 | 1 | 1 | 23 Nov 2017 |
1 detailed pages
Grass carp by river
Open any river-specific page for its measured lengths, largest surveyed individuals, locations and observation history.
Anglian 1 pages
How to read this page
Survey measurements, not angling records
Environment Agency surveys are designed to monitor fish populations. Their largest measurement is not equivalent to a verified rod-and-line record, and the survey sample does not include every river or every grass carp.
Waterway groups with administrative or mixed-river labels are excluded from the headline national totals and rankings. Their eligible river-specific pages remain available in the directory so no published destination is hidden.
The fish records use the Environment Agency source snapshot dated 10 August 2026.
How RiverFish handles the data →