Identification: Koi are a domesticated ornamental carp taxa that vary widely in coloration with combinations of bright gold, orange, silver, white, and black colors patterns (Kottelat and Freyhof 2007). Koi are characterized by their deep body, two barbels on each side of its upper jaw, and serrated dorsal spine (Nelson 1984).
Koi (Cyprinus rubrofuscus) are ornamental varieties of domesticated carp that are often erroneously identified as European Carp (C. carpio) (Kottelat and Freyhof 2007). Wild C. rubrofuscus can be distinguished from wild C. carpio by having 29-33 + 2-3 lateral line scales (vs. 33-37 + 2-3), 18-22.5 branched dorsal rays (vs. 17-20.5), a silvery body with red pelvic, anal, and lower caudal lobes (vs. grey to bronze) (Kottelat and Freyhof 2007).
† Populations may not be currently present.
* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).
Impact of Introduction:
Koi carry and transmit the koi herpesvirus (KHV) disease, which can result in large die-offs of many carp groups (Matsui et al. 2008). The species is also capable of becoming infected with carp oedema virus (CEV), which causes koi sleepy disease (KSD) and results in sickness and the eventual death of the fish from anoxia, which can affect the ornamental koi industry, as there is a 100% motality rate for the disease (Kim et al. 2017).
References: (click for full references)
Dong, C., J. Xu, B. Wang, J. Feng, Z. Jeney, X. Sun, and P. Xu. 2015. Phylogeny and evolution of multiple common carp (Cyprinus carpio L.) populations clarified by phylogenetic analysis based on complete mitochondrial genomes. Marine Biotechnology 17(5):565-575.
Fricke, R., W. N. Eschmeyer, and R. Van der Laan. 2019. Eschmeyer's Catalog of Fishes: Genera, species, references. http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. Accessed on 06/26/2019.
Gross, R., K. Kohlmann, and P. Kersten. 2002. PCR–RFLP analysis of the mitochondrial ND-3r4 and ND-5r6 gene polymorphisms in the European and East Asian subspecies of common carp (Cyprinus carpio L.). Aquaculture 204:507-516.
Kim, S.W., J.W. Jun, S.S. Giri, C. Chi, S. Yun, H.J. Kim, S.G Kim, J.W. Kang, and S.C. Park. 2017. First report of carp oedema virus infection of koi (Cyprinus carpio haematopterus) in the Republic of Korea. Transboundary and Emerging diseases 00:1-6.
Kohlman, K., and P. Kersten. 1999. Genetic variability of German and foreign common carp (Cyprinus carpio L.) populations. Aquaculture 173:435-445.
Kottelat, M., and J. Freyhof. 2007. Handbook of European freshwater fishes. Publications Kottelat, Cornol, Switzerland.
Matsui, K., M. Honjo, Y. Kohmatsu, K. Uchii, R. Yonekura, and Z. Kawabata. 2008. Detection and significance of koi herpesvirus (KHV) in freshwater environments. Freshwater Biology 53:1262-1272.
Nelson, J.S. 1984. Fishes of the World, 2nd Edition. John Wiley & Sons New York.
Popovski, Z., K. Kwasek, M. Wojno, K. Dabrowski, and M. Wick. 2017. Identification and partial characterization of a sex specific protein in Koi carp (Cyprinus carpio haematopterus). Acta Veterinaria-Beograd 67(2):285-291.
Smithsonian National Zoo and Conservation Biology Institute. 2019. Japanese koi. https://nationalzoo.si.edu/animals/japanese-koi. Accessed on 06/27/2019.
Tomelleri, J., M. Eberle. 1990. Fishes of the Central United States. Lawrence, Kansas: University Press of Kansas.
Zhou, J., Z. Wang, Y. Ye, and Q. Wu. 2003b. PCR-RFLP analysis of mitochondrial DNA ND5/6 region among 3 subspecies of common carp (Cyprinus carpio L.) and its application to genetic discrimination of subspecies. Chinese Science Bulletin 48(5):465-468.
Zhou, J., Q. Wu, Y. Ye, and J. Tong. 2003a. Genetic divergence between Cyprinus carpio carpio and Cyprinus carpio haematopterus as assessed by mitochondrial DNA analysis, with emphasis on origin of European domestic carp. Genetica 119:93-97.
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.