crucian carp (Carassius carassius)

Carassius carassius
(crucian carp)
Fishes
Exotic

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Carassius carassius (Linnaeus, 1758)

Common name: crucian carp

Synonyms and Other Names: Crucian Carp, Golden Carp, Gibele, Prussian Carp, English Carp, Carassius vulgaris (Nilsson, 1840), Cyprinus arassius (Linneaus, 1758)

Taxonomy: available through www.itis.gov

Injurious: This species is listed by the U.S. Fish and Wildlife Service as injurious wildlife.

Identification: Distinguishing characteristics were provided by Berg (1964), Muus and Dahlstrom (1978), Wheeler (1978), Raicu et al. (1981), Howells (1992) and Wheeler (2000).

Dorsal rays iii-iv (14-21); Anal rays ii-iii (5-8); Pharyngeal teeth in one row (0,4-4,0); Gill rakers 22-33; lateral line scales 28-37. Dorsal and anal fins have a serrated, spinelike ray. Typically, individuals are deep-bodied and laterally compressed; however, a slender "shallow-body" variety also exists. The body is golden copper, darker dorsally with reddish fins. Barbels are not present around the mouth.

Crucian carp are distinguished from Goldfish (Carassius auratus) as follows:

Character	Crucian Carp	Goldfish
Dorsal fin margin	slightly convex	straight or slightly convex
Caudal fin	slightly emarginate	deeply emarginate
Denticles on posterior margin of dorsal fin	28-29	10-11

Size: To about 50 cm and 5 kg (Berg 1964; Wheeler 1978).

Native Range: Native ranges include Europe and Siberia (Raicu et al. 1981). Recent genetic studies reported in 2017 and 2019 suggest that populations in parts of England may not be native as once thought, but instead introduced by humans (Jeffries et al. 2017, Copp and Sayer 2020). Copp and Sayer (2020) reported that C. carassius was probably introduced in the East of England near the same time as Common Carp Cyprinus carpio based on new genetic evidence, however, C. carassius is still considered a “cultural heritage species” and they recommended conservation and management of the species through fisheries in England.

Alaska

Hawaii

Puerto Rico &
Virgin Islands

Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Carassius carassius are found here.

State	First Observed	Last Observed	Total HUCs with observations†	HUCs with observations†
IL	1910	1910	1	Chicago

Table last updated 1/15/2026

† Populations may not be currently present.

Ecology: Crucian Carp is known for its remarkable hardiness (Muus and Dahlstrom 1978). Historical accounts report the species can live for hours out of the water (Seeley, 1886). The Crucian Carp is tolerant of low-oxygen conditions, high turbidity, low pH (down to 4), and a broad temperature range. It can tolerate temperatures from 0–38 °C (optimum at 27 °C) (Lenkiewicz 1964; Holopainen & Oikari 1992; Holopainen et al. 1997). Survival has been documented at water temperatures below 0°C, and individuals may even survive for a few days with a frozen integument (Szczerbowski and Szczerbowski 2001). In Finland, the shift in energy allocation from growth and reproduction to the accumulation of glycogen occurs in July. These carbohydrate reserves, along with a shift to anaerobic metabolism that decreases metabolic rate to 20-30% of the aerobic rate, help C. carassius survive prolonged periods of anoxia and low temperatures (Holopainen and Hyvärinen 1985; Piironen and Holopainen 1986; Holopainen et al. 1997). In response to hypoxia, this species’ gill will display a protruding lamellae that increases the respiratory surface area allowing the Crucian Carp a greater capacity for oxygen uptake. The efficiency of Crucian Carp haemoglobin in extracting oxygen from the water allows this species to reduce the surface area of its gill filaments during normoxic conditions,which reduces osmoregulatory costs and improves its tolerance to toxic substances (Sollid et al. 2003; Poleo et al. 2017). In their native range, feeding may stop for several months as the fish rest in a state of "suspended animation" during winter months when ponds become anoxic and covered with ice (Zhadin and Gerd 1963, Penttinen and Holopainen 1992). Crucian Carp is a freshwater species, but lab experiments have noted that this species can survive for at least 6 hours in hypersaline water (16 ppm).

Carassius carassius are relatively inactive fish that inhabit littoral zones and tend to locate themselves within habitat structure, especially in the presence of predators (Holopainen et al. 1997). Crucian Carp thrive in shallow ponds with dense, emergent vegetation such as Typha spp. and Phragmites spp. (Wheeler 2000).

Crucian Carp actively feed during the summer months (Penttinen and Holopainen 1992). While planktonic and benthic invertebrates typically form the dominant part of the diet, Carassius carassius will also feed on phytoplankton plant material, and detritus (Penttinen and Holopainen 1992; Holopainen et al. 1997).

Crucian Carp typically have a lifespan of 10 years with males reaching sexual maturity at 3 years and females at 4 in Central and Eastern Europe (Freyhof and Kottelat 2008).

Crucian Carp spawn intermittently from late spring through mid-summer, after water temperatures have reached the required threshold of 17-20 °C (Holopainen et al. 1997). This species is a phytophilous, open substrate spawner with eggs that adhere to submerged structures and macrophytes (Holopainen et al. 1997). Relative and absolute fecundity varies among populations and environments and increases with size. Average relative fecundity of Crucian Carp in Lake Varaslampi was 129.2 eggs/g of fish, which would amount to an absolute fecundity of 121,822.7 for an average sized female in that lake (942.9 g wet mass) (Holopainen et al. 1997). Fertilized eggs were found to develop normally in laboratory conditions at 15-28 °C, but died at 5, 10, and 30 °C. Temperatures of 24-28 °C resulted in the quickest (>3 days) incubation from fertilization to the free embryo stage. In Scandinavian ponds, hatching took six days at 18-19 °C (Holopainen et al 1997).

Growth rates can be highly variable and are believed to be strongly influenced by population densities and food availability. In their first year of life, Carassius carassius have been observed to range in size from 2.2 to 10.9 cm depending on the population density, environment, and when an individual was born during the spawning season (Skora 1982, Holopainen et al. 1997).

This species occurs regularly in small ponds (often as a monoculture assemblage) as well as in larger lakes with high species richness. Crucian Carp exhibit two distinct morphologies which are reported to be driven predominantly by the fish community assemblage. Particularly, the existence of “pond” and “lake” forms of Crucian Carp are believed to be strongly related to the presence or absence of predators more than environmental or physical characteristics of the water body. In Swedish lakes, Crucian Carp population density and size were significantly smaller (mean size 9.2 cm, 20 g) in ponds and lakes without piscivores than in water bodies with piscivores (mean size 31.3 cm, 735 g) (Bronmark et al. 1995). However, growth-stunted, low-bodied (‘pond’ form) Crucian Carp were observed to shift their deep-bodied form (‘lake’ form) when introduced into a fishless, productive pond. This suggests that two different conditions can induce Crucian Carp to grow into the deep-bodied lake forms: 1) the presence of piscivorous fish and 2) increased food availability in the absence of piscivorous fish (Holopainen et al. 1997).

Status: There are no recent reports of Carassius carassius in the United States. An earlier report that either C. carassius or a hybrid (with goldfish) had been introduced into Texas (Howells 1992) is now considered unlikely. Meek and Hildebrand (1910) reported that Crucian Carp were thriving within lagoons of parks the greater Chicago area, but Smith (1979) suggests that the population was extirpated shortly after publication of Meek and Hildebrand (1910). The introduction and status of this species remains uncertain.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Because of this species' similarity to goldfish, and because of possible hybridization, characters may overlap and positive identification may be difficult. Similar to Goldfish, Crucian Carp is known to hybridize with the Common Carp Cyprinus carpio (Berg 1964; Muus and Dahlstrom 1978; Wheeler 1978). Eddy and Underhill (1974) reported that both Goldfish and Crucian Carp had been introduced into the United States, but they provided no additional details concerning the latter species. Welcomme (1988) reported that C. carassius was established in Chicago in the 1900s but later died out; however, he did not provide documentation for that record and we have found no additional information to support it.

There is some confusion in the literature surrounding the use of the names Crucian Carp and Prussian Carp. Lever (1996) listed Prussian Carp as an alternative or local vernacular name sometimes used for the Crucian Carp; however, Berg (1964) and most others use the name Prussian Carp for Carassius auratus gibelio. In the 1800s Baird witnessed fish taken out of the Hudson River, New York; Baird later wrote that these fish appeared to be "hybrids between goldfish and the Prussian carp" (Redding 1884). In that instance it is not certain as to which species Baird is referring to in using the term Prussian Carp. Cole (1905) quoted from one of Baird's reports, in which Prussian Carp is treated as synonymous with Cyprinus carassius (=Carassius carassius?).

No known voucher specimens.

References: (click for full references)

Berg, L.S. 1964. Freshwater Fishes in the U.S.S.R. and Neighbouring Countries. Vol. 2., Fourth edition. Translated from Russian by Israel Program for Scientific Translations, Jerusalem, IPST Catalog No. 742. 496 pp.

Boogaard, M.A., T.D. Bills, J.H. Selgeby, and D.A. Johnson. 1996. Evaluation of piscicides for control of ruffe. North American Journal of Fisheries Management 16(3):600-607. https://doi.org/10.1577/1548-8675(1996)016<0600:EOPFCO>2.3.CO;2.

Bronmark, C., C.C. Pazkawoski, W.M. Tonn, and A. Hargeby. 1995. Predation as a determinant of size structure in populations of crucian carp (Carassius carassius) and tench (Tinca tinca). Ecology of Freshwater Fish 4:85-92.

Cole, L. J. 1905. The German carp in the United States. Pages 523-641 in Report of the Bureau of Fisheries for 1904. U.S. Department of Commerce and Labor. Government Printing Office, Washington, D.C.

Eddy, S., and J. C. Underhill. 1974. Northern fishes, with special reference to the Upper Mississippi Valley, 3rd edition. University of Minnesota Press, Minneapolis, MN.

Fuller, P. L., L. G. Nico, J. D. Williams. 1999. Nonindigenous Fishes Introduced Into Inland Waters of the United States. Special Publication 27, American Fisheries Society. Bethesda, Maryland. 613 pp.

Holopainen, I.J., and H. Hyvärinen. 1985. Ecology and physiology of crucian carp [Carassius carassius (L.)] in small Finnish ponds with anoxic conditions in winter. Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen 22(4):2566-2570. https://www.tandfonline.com/doi/abs/10.1080/03680770.1983.11897726.

Holopainen, I.J., W.M. Tonn, and C. A. Paszkowski. 1997. Tales of two fish: the dichotomous biology of crucian carp (Carassius carassius L. ) in northern Europe. Annales Zoologici Fennici 34:1-22.

Howells, R. G. 1992. Guide to identification of harmful and potentially harmful fishes, shellfishes and aquatic plants prohibited in Texas. Texas Parks and Wildlife Department Special Publication, Austin, TX. 182 pp. (+ appendices).

Lappalainen, J., Vinni, M., Malinen, T., 2013. Consumption of Crucian Carp (Carassius carassius L., 1758) by restocked pike (Esox lucius L., 1758) in a lake with frequent winter hypoxia. Journal of Applied Ichthyology 29:1286–1291. https://doi.org/10.1111/jai.12284

Lever, C., 1996, Naturalized fishes of the world: Academic Press, 408 p.

Marking, L.L., T.D. Bills, J.J. Rach, and S.J. Grabowski. 1983. Chemical control of fish and fish eggs in the Garrison Diversion Unit, North Dakota. North American Journal of Fisheries Management 3(4):410-418. https://doi.org/10..1577/1548-8659(1983)3<410:CCOFAF>2.0.CO;2.

Muus, B.J., and P. Dahlstrom. 1978. Collins guide to the freshwater fishes of Britain and Europe. Collins, London, England. 222 pp.

Meek, S.E., and Hildebrand, S.F. 1910. A synoptic list of the fishes known to occur within fifty miles of Chicago: Field Museum of Natureal History, Publication 142, Zoological Series, 7(9):223-338.

Meronek, T.G., P.M. Bouchard, E.R. Buckner, T.M. Burri, K.K. Demmerly, D.C. Hatleli, R.A. Klumb, S.H. Schmidt, and D.W. Coble. 1996. A review of fish control projects. North American Journal of Fisheries Management 16:63-74. https://doi.org/10.1577/1548-8675(1996)016<0063:AROFCP>2.3.CO;2.

Patrick, P.H., A.E. Christie, D. Sager, C. Hocutt, and J. Stauffer, Jr. 1985. Responses of fish to a strobe light/air-bubble barrier. Fisheries Research 3:157-172. https://doi.org/10.1016/0165-7836(85)90016-5

Penttinen, O.-P. and I.J. Holopainen. 1992. Seasonal feeding activity and ontogenetic dietary shifts in Crucian carp, Carassius carassius. Environmental Biology of Fishes 33(1-2):215-221.

Piironen, J., and I.J. Holopainen. 1986. A note on seasonality in anoxia tolerance of Crucian carp (Carassius carassius [L.]) in the laboratory. Annales Zoologici Fennici 32:335-338.

Raicu, P., E. Taisescu, and P. Banarescu. 1981. Carassius carassius and C. auratus, a pair of diploid and tetraploid representative species (Pisces, Cyprinidae). Cytologia 46:233-240 .

Redding, J.D. 1884. Character of the carp introduced by Capt. Henry Robinson about 1830. Bulletin of the U.S. Fish Commission 4(1884):266-267.

Seeley, H.G. 1886. The Freshwater Fishes of Europe. Cassell and Company, Ltd. London. 444 pp.

Smith, P.W. 1979. The Fishes of Illinois. University of Illinois Press, Urbana, IL. 314 pp.

Szczerbowski, J.A., and A.J. Szczerbowski. 2002. Carassius carassius (Linnaeus, 1758). Pages 43-78 in Banarescu, P., M., and H.J. Paepke, eds. The freshwater fishes of Europe. Volume 5/III. Aula-Verlag. Wiebelsheim, Germany.

Welcomme, R.L. 1988. International introductions of inland aquatic species. FAO Fisheries Technical Paper 294. Food and Agriculture Organization of the United Nations (FAO), Rome, Italy. 318 pp.

Wheeler, A. 1978. Key to the fishes of northern Europe. Frederick Warne Ltd., London, England.

Wheeler, A. 2000. Status of the crucian carp, Carassius carassius (L.) in the UK. Fisheries Management and Ecology 7:315-332.

Zhadin, V. I. and S. V. Gerd. 1963. Fauna and Flora of the Rivers Lakes and Reservoirs of the U.S.S.R. Originally published in Moskow, 1961 by Gosudarstvennoe Uchebno-Pedagogicheskoe Izdatel'stvo Misisterstva Prosveshcheniya RSFSR. Translated from Russian in 1963 by the Israel Program for Scientific Translations, Jerusalem. 626 pp.

Other Resources:
US Fish and Wildlife Service Ecological Risk Screening Summary for Carassius carassius

FishBase Summary

Author: Schofield, P.J., L.G. Nico, P. Fuller, A. Fusaro, A. Davidson, K. Alame, M. Gappy, W. Conard, P. Alsip, B. Nielsen, A.S. Mulligan and R. Sturtevant

Revision Date: 12/23/2025

Peer Review Date: 9/15/2011

Citation Information:
Schofield, P.J., L.G. Nico, P. Fuller, A. Fusaro, A. Davidson, K. Alame, M. Gappy, W. Conard, P. Alsip, B. Nielsen, A.S. Mulligan and R. Sturtevant, 2026, Carassius carassius (Linnaeus, 1758): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=509, Revision Date: 12/23/2025, Peer Review Date: 9/15/2011, Access Date: 1/16/2026

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.

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