Crucian Carp (Carassius carassius) - Species Action Plan

A cryptic, mainly benthic, freshwater fish, with a long dorsal fin (without barbs), a rounded forehead and no barbels. Normally of olive golden-brown colour, the pelvic fins are pinkish with the first ray having darker (blackish) pigmentation. Found in freshwater systems, but characteristic of ponds and river backwaters.
Ref LS/3 Local Species Action Plan 3
Plan Authors: G.H. Copp (Cefas/BU) and C.D. Sayer (UCL)
Plan Co-ordinator: Waterbodies BAP Topic Group
Plan Leaders: UCL and Cefas/BU
Stage: Final Date: Feb 2010
Plan Duration: Six Years: Feb 2010 to Jan 2016

Action Plan Summary

Current Status

International and National Status

  • Crucian carp Carassius carassius is classified in the IUCN Red List of Threatened Species as 'Least Concern', but with the caveat: Population trend: decreasing. Evidence of, and reasons for, the latter have been attributed to acidification (Holopainen & Ikari 1992), loss of habitat (Copp 1991, Schwevers et al. 1999), displacement by introduced gibel carp (Navodaru et al. 2002), and extirpation by introduced goldfish Carassius auratus and common carp Cyprinus carpio through hybridization (Wheeler 2000, Hänfling et al. 2005, Smartt 2007). Indeed, recent unpublished genetic analysis has revealed that fish in northern France thought to be C. carassius are in fact gibel carp (Carassius gibelio), the same species blamed for the decline of C. carassius in the Lower Danube (Navodaru et al. 2002).
  • With a native distribution originally limited to southeast England (Wheeler 1972, 2000), records of C. carassius distribution since 1960 include sites throughout most of England and parts of Wales (Marlborough 1967a, Maitland 1972, Davies et al. 2004).
  • The species' distribution is, however, unreliable because of confusion between C. carassius and the natural brown variety of C. auratus (Wheeler 2000, Hickley & Chare 2004), including erroneous reference to gibel (aka Prussian) carp C. gibelio (see Wheeler 2000).
  • Carassius carassius is recognised in both local (Conservators of Epping Forest 2002, Lambeth Borough Council 2006, London Councils 2007) and national (Environment Agency 2003, 2008) initiatives to educate the public about the plight of the species and its conservation.

Norfolk Status

  • The region of Norfolk and northern Suffolk, but excluding the Broads (Ellis 1965), is thought to be a stronghold for C. carassius (Copp & Sayer 2009). Other neighbouring counties within the native C. carassius range include Middlesex (Marlborough 1967b), Essex (Wheeler 1998, Tarkan et al. 2009), Hertfordshire (Copp et al. 2008a, 2008b), the counties encompassed by the Lower Thames catchment (i.e. Middlesex, Surrey, Kent) and possibly Cambridgeshire.
  • Recent research on the distribution of C. carassius in Norfolk (Copp & Sayer 2009, Sayer et al., submitted) has revealed a species occurrence decline of around 75% between the 1970s and 2008–2009 (of 28 ponds known to have contained C. carassius in the 1970s, only five retained the species). This decline is well above the 25% and 50% declines stipulated in the second and third BAP criteria, respectively (Copp & Sayer 2009).

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Current factors causing loss or decline in Norfolk

The threats to this species in the Norfolk (and neighbouring counties) include:

  • Genetic contamination through hybridization with introduced Carassius auratus and varieties of common carp Cyprinus carpio (Hänfling et al. 2005, Smartt 2007), including 'koi' and 'chagoi', which are released illegally into open waters (Copp et al. 2005).
  • Loss of habitat due to river regulation (Copp 1991; Schwevers et al. 1999, Navodaru et al. 2002).
  • Changes in agricultural and landuse practices, especially the terrestrialisation of ponds (Schwevers et al. 1999, Sayer et al., submitted).
  • A previous lack of recognition of C. carassius as a characteristic pond species (see Copp et al. 2008b)

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Current Action in Norfolk

  • Carassius carassius is a central component of pond conservation initiatives in North Norfolk, led by Dr. Carl Sayer (UCL-London), which has led to an established and increasing interest amongst land owners and anglers in C. carassius conservation.
  • A village meeting was held in Bodham (near Holt, Norfolk) in spring 2009 to inform local stakeholders on initiatives into the conservation of C. carassius in north Norfolk.
  • The character (water chemistry, aquatic invertebrates and plants) of ponds inhabited by C. carassius in north Norfolk is being assessed by Cefas and UCL along side assessments of the species' status in order to aid conservation initiatives.
  • A tissue library has been established, which will be analysed once the necessary funds are obtained, so as to determine whether or not C. carassius populations in Norfolk are genetically distinct within England and within its native European range.

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Action Plan Objectives and Targets


As C. carassius has not yet been included on the UK list of priority species, there are no national BAP objectives or targets for this species. Note, however, that the Environment Agency (national level) has begun to raise public awareness about concerns regarding the decline of C. carassius (Environment Agency 2003) and it has also restocked the species into some appropriate water bodies, e.g. in Norfolk (Environment Agency 2008).



  • Determine the genetic character of English C. carassius. This has received only limited study in the UK (Hänfling et al. 2005), and this work did not shed any light on the amount of genetic variability within England (i.e. are Norfolk C. carassius unique relative to other parts of the UK?), nor within the species' native European range. Prior to any restocking of the species (from sources outside Norfolk), one of the objectives of this plan is to complete a genetic analysis of existing tissue samples from populations in north Norfolk, Hertfordshire and Essex (stored at Cefas-Lowestoft) as well as from the EA brood stock population at Culverton. Progress will be reported from research that is anticipated for autumn 2011, pending financial support for completion of the laboratory analysis, aiming to advise management plans with particular regard to the sources of fish used in the rehabilitation (i.e. stocking) of existing populations and the re-introduction of the species to appropriate ponds (e.g. where previously present but subsequently extirpated).
  • Acquire baseline information on population status and distribution across the county;
  • Increase the number of viable populations in a 'pilot' area of the county (North Norfolk);
  • Raise awareness of the species' importance and conservation needs.


  • Range - Based on the results of research by Sayer et al. (submitted), a 75% reduction in C. carassius range is assumed throughout North Norfolk for the last three decades. The target for the five year period of 2010 to 2015 will be to double the current range in North Norfolk (i.e. increase from 20 % to 40 % occurrence in ponds that were known previously to contain crucian carp) through restocking and habitat enhancement. Progress towards this target will be reported from a survey (i.e. estimate of range) that is anticipated for spring 2015.
  • Population Size - The survey results for North Norfolk (Sayer et al., submitted) indicate that only one population of C. carassius (from 22 ponds surveyed, 5 %) was sufficiently abundant to be considered 'self sustaining'. The target for 2015 is to double the proportion of ponds in North Norfolk (known previously to contain the species) with self-sustaining populations (i.e. from 5 to 10 %) through restocking and habitat enhancement. Progress towards this target will be reported from a population survey that is anticipated for spring 2015.

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