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Taxonomic name: Hypophthalmichthys molitrix (Valenciennes in Cuvier and Valenciennes, 1844) Synonyms: Abramocephalus microlepis Steindachner, 1869 , Cephalus mantschuricus Basilewsky, 1855 , Hypophthalmichthys dabry Guichenot, 1871 , Hypophthalmichthys dybowskii Herzenstein, 1888 , Hypophthalmichthys molitrix (Valenciennes, 1844) , Hypothalmichthys molitrix (Valenciennes, 1844) , Hypothamicthys molitrix (Valenciennes, 1844) , Leuciscus hypophthalmus Richardson, 1945 , Leuciscus molitrix Valenciennes, 1844 , Onychodon mantschuricus Basilewsky, 1872 Common names: amour argenté (French), asimokyprinos (Greek), ballgjeri i bardhe (Albanian), belli-gende (Kanarese), belyi tolstolob (Russian), belyi tolstolobik (Russian), bin ue (Cantonese), byal tolstolob (Bulgarian), carpa argentata (Italian), carpa plateada (Spanish), carpa-prateada (Portuguese), carpe argentée (French), carpe asiatique (French), carpe chinoise (French), Chinese schemer (English), cho ue (Cantonese), crap argintiu (Romanian), crap-chinezesc-argintiu (Romanian), fehér busa (Hungarian), fytofag (Farsi), hakuren (Japanese), hopeapaksuotsa (Finnish), kap perak (Malay), kasaf (Hebrew), kopur noqreai (Farsi), lin ue (Cantonese), phytophague (Farsi), pla leng hea (Thai), pla leng heu (Thai), pla lin (Thai), pla pae long (Thai), pla pin hea (Thai), pla pin heu (Thai), silberkarpfen (German), silver carp (English), silverkarp (Swedish), silwerkarp (Afrikaans), sølvkarpe (Danish), Sølvkarpe (Norwegian), tolpyga (Russian), tolpyga biala (Polish), tolstolob (German), tolstolob biely (Slovak), tolstolobik (Russian), tolstolobik bílý (Czech), tolstolobik obecný (Czech), tongsan putih (Malay), toplyga biala (Polish), tovstolob zvychajnyi (Ukrainian), zilverkarper (Dutch) Organism type: fish Hypophthalmichthys molitrix is a carp, native to Asia. Hypophthalmichthys molitrix have been introduced around the world for aquaculture purposes and also for controlling excessive growth of phytoplankton in natural waters. Hypophthalmichthys molitrix have the potential to reduce native diversity by competing for and depleting zooplankton populations, altering the food web. Hypophthalmichthys molitrix have also been found to carry and transmit the disease Salmonella typhimurium. Description The Gulf States Marine Fisheries Commission (2003) states that, "H. molitrix are large, laterally compressed cyprinids with a uniform silver colouration. There are between 95 and 103 scales in the lateral line. The mouth is relatively large, upturned and toothless. Small specimens do not have spines on their fins, whereas large specimens have a hard, stiff spine with fine serrae on its posterior margin, at the front end of the pectoral, and moderately strong spines in their dorsal and anal fins. The dorsal fin origin is behind the pelvic fin insertion. There are 8 dorsal rays and 12-13 anal rays. The pharyngeal teeth count is 4-4. The gill rakers are fused into a sponge-like porous plate (Robison and Buchanan, 1988)." "Silver carp (H. molitrix) are a distinctive bright silver. They have small scales and no barbels" (Atlas of New Zealand Freshwater Fishes, 2005). FishBase (2005) reports that, "H. molitrix is an active species well known for its habit of leaping clear of the water when disturbed. It swims just beneath the water surface." Similar Species Aristichthys nobilis More Occurs in: lakes, water courses Habitat description The Gulf States Marine Fisheries Commission (2003) report that H. molitrix are fresh water species and are not found in saline waters. While the species can inhabit lakes and ponds, for spawning to occur it requires moving water with sufficient current to allow proper egg development. Spawning of H. molitrix is similar to Aristichthys nobilis in that it occurs in swift channels of large rivers. Flooding of lowland areas is a necessary requirement as these become the nursery areas for larvae and juveniles (Burr et al. 1996). General impacts Burr et al. (1996) state that, "The potential impact of H. molitrix and A. nobilis (Aristichthys nobilis) is not adequately known. Markets for these carp apparently have not become well established. Confusion over the correct identity of these species and the legality of taking this fish in commercial harvests has resulted in its consideration as a nuisance by some fishermen we have interviewed." The Gulf States Marine Fisheries Commission (2003) states that, "H. molitrix are capable of consuming large quantities of phytoplankton. Nonetheless, potential effects of this species' introductions are difficult to assess. If stable breeding populations were to form and the number of individuals became abundant, shifts in food web structure could be expected. Although reported to consume mostly phytoplankton, and equipped with a highly specialized filtering apparatus, H. molitrix consume whatever form of plankton is available in its environment. Where phytoplankton is scarce this species will consume zooplankton (Spataru and Gophen, 1985; Burke et al. 1986). Spataru and Gophen (1985) have reported declines in zooplankton biomass which they attribute to stocked H. molitrix." The Gulf States Marine Fisheries Commission (2003) states that, "H. molitrix can transport diseases to new areas. Bocek et al. (1992) found this species to be an effective carrier of Salmonella typhimurium." Uses Elvira (2001) reports that, " H. molitrix have been widely introduced specifically to control excessive growths of phytoplankton in natural waters." Notes Recent research has shown that certain cultural practices are also confounding carp management. Higbee et al. (2004) state that, "It has been discovered that an increasing population within the Great Lakes region uses live invasive fish for religious and cultural purposes. Asian carp, such as H. molitrix, have been discovered in public ponds and lagoons in the Great Lakes region, and media stories indicate that these fish are being intentionally released as part of a religious ceremony. The hojo-e ceremony of releasing living beings into the wild is a ritual performed in a number of Buddhist countries, particularly in Eastern Asia. The ritual, developed in Japan, is based on the principle of compassionate action toward animals to accrue merit for the afterlife. Followers of this tradition believe that performing good deeds such as releasing captive animals will lengthen their own life span. Although this practice occurs in the United States (where it is common to release goldfish, turtles, and birds), this ritual is usually performed in a pond at a Buddhist temple under the guidance of a monk. In the Czech Republic, it is tradition to keep a live carp in the bathtub for a few days before a Christmas feast. It has been found that some people buy two; one to eat, and one to release into a river". Geographical range Native range: China and Russia (Nguyen and Nakorn, 2004; and Elvira, 2001). Known introduced range: Africa, Asia, Australasia-Pacific, North America, and South America (FishBase, 2005; Elvira, 2001; Champion et al. 2002; Stone et al. 2000; and Garcia et al. 2004). Introduction pathways to new locations Aquaculture: H. molitrix were initially introduced into U.S. waterways through their unintentional escape from southern aquaculture facilities. Accidental release of H. molitrix from these facilities resulted from 1990 floods in the Mississippi River system (Higbee et al. 2004). Landscape/fauna "improvement": The silver carp H. molitrix was imported in 1973 for phytoplankton control in eutrophic water and as a food fish. This species hitchhiked to Florida in a shipment of grass carp for vegetation control (Middlemas 1994). Live food trade: It is suspected that the live food fish industry could be a potential pathway for introducing Asian carp into Great Lakes waters (Higbee et al. 2004). Local dispersal methods Intentional release: Higbee et al. (2004) state that, "It has been discovered that an increasing population within the Great Lakes region uses live invasive fish for religious and cultural purposes. Asian carp have been discovered in public ponds and lagoons in the Great Lakes region, and media stories indicate that these fish are being intentionally released as part of a religious ceremony." Management information Higbee et al. (2004) states that, "A regulatory approach of identifying legal responsibility and developing consistent regulations will be needed on a regional basis to prevent intentional or unintentional release of invasive species including carp such as H. molitrix. Managers, however, must also contend with the reality that the absence of adequate enforcement mechanisms compromises the effectiveness of these regulations." Nutrition The Atlas of New Zealand Freshwater Fishes (2005) states that, "H. molitrix feed by filtering phytoplankton from the water using specialized gill structures to do so and their gut is greatly elongated to aid digestion of their food." "With its spongelike gill rakers, H. molitrix is capable of straining organisms as small as 4 microns in diameter and is apparently efficient at digesting green and bluegreen algae (Robison and Buchanan 1988)" (Burr et al. 1999)." Though removal rates of silver carp are highest in the particle size range 17 to 70 microns (Dong and Li 1994) Reproduction The Gulf States Marine Fisheries Commission (2003) reports that H. molitrix require bodies of water with some current for eggs to float and develop properly. Carp carry out migrations to communal spawning grounds during spring flooding. The prefer to spawn in small groups of 15 to 25 fish at dusk and dawn, at water temperatures of between 18-20°C. Typical spawning age can be from 3 to 10 years old. Females can lay from 299 to 5400 eggs (The Gulf States Marine Fisheries Commission, 2003). Lifecycle stages H. molitrix require bodies of water with some current for eggs to float and develop properly. Carp carry out migrations to communal spawning grounds during spring flooding. The prefer to spawn in small groups of 15 to 25 fish at dusk and dawn, at water temperatures of between 18-20°C. Typical spawning age can be from 3 to 10 years old. Females can lay from 299 to 5400 eggs (The Gulf States Marine Fisheries Commission, 2003). Reviewed by: Dr. Robert J. Radke Fish Ecologist Germany Principal sources: Higbee et al. 2004. The Live Food Fish Industry: New Challenges in Preventing the Introduction and Spread of Aquatic Invasive Species Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG) Last Modified: Tuesday, 11 April 2006