Historic monitoring evidence · Environment Agency
Denham
Hertfordshire and North London · survey site
This page records ecological survey evidence. It is not proof of current fish presence, abundance, fishing quality, access, permission or safety at this location.
Observed taxa
What monitoring recorded here
Taxa are ordered by latest survey date. Counts and records reflect monitoring events, not an angling forecast.
Roach
Rutilus rutilus- First record
- 20 Oct 1998
- Latest record
- 16 Jul 2015
- Survey events
- 8
Bullhead
Cottus gobio- First record
- 8 Sept 2003
- Latest record
- 16 Jul 2015
- Survey events
- 7
Minnow
Phoxinus phoxinus- First record
- 1 Dec 2004
- Latest record
- 16 Jul 2015
- Survey events
- 4
Perch
Perca fluviatilis- First record
- 20 Oct 1998
- Latest record
- 26 Jun 2012
- Survey events
- 9
Dace
Leuciscus leuciscus- First record
- 20 Oct 1998
- Latest record
- 26 Jun 2012
- Survey events
- 5
European eel
Anguilla anguilla- First record
- 18 Nov 2005
- Latest record
- 26 Jun 2012
- Survey events
- 5
Pike
Esox lucius- First record
- 20 Oct 1998
- Latest record
- 26 Jun 2012
- Survey events
- 4
Bleak
Alburnus alburnus- First record
- 18 Nov 2005
- Latest record
- 26 Jun 2012
- Survey events
- 3
Brown / sea trout
Salmo trutta- First record
- 5 Oct 2006
- Latest record
- 3 Aug 2010
- Survey events
- 2
Barbel
Barbus barbus- First record
- 5 Oct 2006
- Latest record
- 1 Aug 2009
- Survey events
- 4
Gudgeon
Gobio gobio- First record
- 20 Oct 1998
- Latest record
- 1 Aug 2009
- Survey events
- 4
Pike varieties
Esox lucius- First record
- 29 Jul 2008
- Latest record
- 1 Aug 2009
- Survey events
- 2
Chub
Leuciscus cephalus- First record
- 1 Dec 2004
- Latest record
- 29 Jul 2008
- Survey events
- 4
European eels > elvers
Anguilla anguilla- First record
- 1 Dec 2004
- Latest record
- 9 Aug 2007
- Survey events
- 2
Ruffe
Gymnocephalus cernuus- First record
- 9 Aug 2007
- Latest record
- 9 Aug 2007
- Survey events
- 1
Silver bream
Abramis bjoerkna- First record
- 9 Aug 2007
- Latest record
- 9 Aug 2007
- Survey events
- 1
Common bream
Abramis brama- First record
- 1 Dec 2004
- Latest record
- 5 Oct 2006
- Survey events
- 2
Tench
Tinca tinca- First record
- 1 Dec 2004
- Latest record
- 5 Oct 2006
- Survey events
- 2
Roach x common bream hybrid
Rutilus rutilus x Abramis brama- First record
- 18 Nov 2005
- Latest record
- 18 Nov 2005
- Survey events
- 1
3-spined stickleback
Gasterosteus aculeatus- First record
- 1 Dec 2004
- Latest record
- 1 Dec 2004
- Survey events
- 1
Rules and access
Check before you travel.
Environment Agency ecology records do not carry fishing-rights boundaries or live restrictions. Confirm the fishery owner, permission, local byelaws, seasonal rules, safety notices and current conditions before setting out.
Check live freshwater fishing rulesProvenance
Source, licence and boundary
- SourceEnvironment Agency Ecology & Fish Data
- LicenceOpen Government Licence v3.0
- Source copy retrieved23 Jul 2026
- Terms checked23 Jul 2026
- CoverageHistoric monitoring evidence, separately dated per record
- Not assertedCurrent presence, access, permission, fishing quality or safety