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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Green Swordtail

Synonyms and Other Names: Xiphophorus helleri (original spelling ends with -ii; Nelson et al. 2004), red swordtail, swordtail.

Taxonomy: available through www.itis.gov

Identification: Distinguishing characteristics were given by Rosen (1960, 1979) and Page and Burr (1991). This species is included in keys of Rosen (1960, 1979), Brown (1971), Minckley (1973), Greenfield and Thomerson (1997), and Miller et al. (2005). Photographs or illustrations appeared in Rosen (1979), Mills and Vevers (1989), Axelrod et al. (1985), Petrovicky (1988), Dawes (1991), Sakurai et al. (1993), and Wischnath (1993).

Size: Females to 16 cm TL; males to 14 cm TL

Native Range: Middle America from Rio Nautla (= Rio Nantla), Veracruz, Mexico, to northwestern Honduras (Rosen 1960, 1979; Page and Burr 1991; Greenfield and Thomerson 1997; Miller et al. 2005).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

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

Ecology: Inhabits fast-flowing streams and rivers around vegetation, and also lives in warm springs, ponds, and ditches (Miller et al. 2005)

Means of Introduction: Most introductions probably due to aquarium releases. Its origin in the Westminster flood control channel in California was believed to be a goldfish farm (St. Amant and Hoover 1969). Florida records may also be fish farm escapes or aquarium releases.

Status: It is locally established, or possibly so, in Colorado (Zuckerman and Behnke 1986), Florida (Nico, personal communication), Hawaii (Devick 1991), Idaho (Courtenay and Meffe 1989), Montana (Courtenay and Meffe 1989), Nevada (Courtenay and Meffe 1989), Texas (Howells 1992), and Wyoming (Stone 1995). A breeding population existed in Arizona at Rock Spring, but it disappeared after a flood in 1965 (Minckley 1973). It has been reported from several sites in California (Dill and Cordone 1997) and a single locality in Oklahoma (Pigg et al. 1996).

Impact of Introduction: Largely unknown. The green swordtail has been implicated in the decline of the Utah sucker Catostomus ardens in a thermal spring in Wyoming (Courtenay et al. 1988). Green swordtails, and other introduced poeciliids, have been implicated in the decline of native damselflies on Oahu, Hawaii. Often the distributions of the damselflies and introduced fishes were found to be mutually exclusive, probably resulting from predation by the fish on the insects (Englund 1999).

Remarks: This species exhibits a wide natural range of body form and color patterns (Rosen 1960, 1979; Dawes 1991; Wischnath 1993). It has long been popular as an ornamental fish, and has been used in genetics research. Many ornamental swordtails are hybrids of X. hellerii with the either X. maculatus or X. variatus.

The green swordtail was recorded from Indian Spring, Clark County, Nevada, as early as 1975 (Courtenay and Deacon 1982). However, the Xiphophorus taken from Indian Spring during later collections were identified as hybrids of X. hellerii x X. maculatus (Courtenay and Deacon 1982; Deacon and Williams 1984; Page and Burr 1991). That conclusion apparently was based on the fact that the live fish were yellow to pale orange (Courtenay and Deacon 1982). In 1989, Rauchenberger (personal communication) examined the preserved voucher material (UF 91919) and determined that all specimens were X. hellerii. Nevertheless, some of the other above records actually may represent hybrids rather than pure X. hellerii. Myers (1940) mentioned an unconfirmed report of X. hellerii breeding in the Florida Everglades; however, no Xiphophorus spp. are known to have established there (Loftus, personal communication).

This species is shown through experimentation to be an alternative host to the glochidia of native unionid mussels Lampsilis cardium and Utterbackia imbecillis (Watters and O'Dee 1998).

Voucher specimens: Colorado (MSB, uncataloged); Florida (USNM 89437; UF 30867, 86323, 91920, 92139, 97844, 98928, 141304, 171132, 171171, 171349, 171711, 171716, 171717, 171720), Hawaii (ANSP 89277; BPBM 35798; UF 119873, 119877), Idaho (UMMZ 213370, 213372), Montana (UMMZ 188982, 188983), Nevada (TU 94348; UF 91919), Oklahoma (OSU 27459).

References: (click for full references)

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Brock, V.E. 1960. The introduction of aquatic animals into Hawaiian waters. Internationale Revue der gesamten Hydrobiologie 45(4):463-480.

Brown, C.J.D. 1971. Fishes of Montana. Montana State University, Bozeman, MT.

Coots, M. 1956. The yellow perch, Perca flavescens (Mitchill), in the Klamath River. California Fish and Game 47(7):219-228.

Courtenay, W.R., Jr. 1985. Florida Atlantic University Quarterly Reports for 1985 to the U.S. Fish and Wildlife Service, Gainesville, FL.

Courtenay, W.R., Jr., and J.E. Deacon. 1982. Status of introduced fishes in certain spring systems in southern Nevada. Great Basin Naturalist 42(3):361-366.

Courtenay, W.R., Jr., and D.A. Hensley. 1979. Survey of introduced non-native fishes. Phase I Report. Introduced exotic fishes in North America: status 1979. Report Submitted to National Fishery Research Laboratory, U.S. Fish and Wildlife Service, Gainesville, FL.

Courtenay, W.R., Jr., D.A. Hensley, J.N. Taylor, and J.A. McCann. 1984. Distribution of exotic fishes in the continental United States. 41-77 in W.R. Courtenay, Jr., and J.R. Stauffer, Jr., eds. Distribution, biology and management of exotic fishes. John Hopkins University Press Baltimore, MD.

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Courtenay, W.R., Jr., and G.K. Meffe. 1989. Small fishes in strange places: a review of introduced poeciliids. 319-331 in G.K. Meffe, and F.F. Snelson, Jr., eds. Ecology and evolution of livebearing fishes (Poeciliidae). Prentice Hall, Englewood Cliffs, NJ.

Courtenay, W.R., Jr., and C.R. Robins. 1973. Exotic aquatic organisms in Florida with emphasis on fishes: a review and recommendations. Transactions of the American Fisheries Society 102:1–12.

Courtenay, W.R., Jr., C.R. Robins, R.M. Bailey, and J.E. Deacon. 1988. Records of exotic fishes from Idaho and Wyoming. Great Basin Naturalist 47(4):523-526.

Courtenay, W.R., Jr., H.F. Sahlman, W.W. Miley, II, and D.J. Herrema. 1974. Exotic fishes in fresh and brackish waters of Florida. Biological Conservation 6(4):292-302.

Dawes, J.A. 1991. Livebearing fishes. A guide to their aquarium care, biology and classification. Blandforn, London, England.

Deacon, J.E., and J.E. Williams. 1984. Annotated list of the fishes of Nevada. Proceedings of the Biological Society of Washington 97(1):103-118.

Deacon, J.E., C. Hubbs, and B.J. Zahuranec. 1964. Some effects of introduced fishes on the native fish fauna of southern Nevada. Copeia 1964(2):384-388.

Devick, W.S. 1991. Patterns of introductions of aquatic organisms to Hawaiian freshwater habitats. Pages 189-213 in new directions in research, management and conservation of Hawaiian freshwater stream ecosystems. Proceedings of the 1990 symposium on freshwater stream biology and fisheries management, Division of Aquatic Resources, Hawaii Department of Land and Natural Resources.

Dial, R.S., and S.C. Wainright. 1983. New distributional records for non-native fishes in Florida. Florida Scientist 46(1):8-15.

Dill, W.A., and A. J. Cordone. 1997. History and status of introduced fishes in California, 1871-1996. California Department of Fish and Game, Fish Bulletin 178:1-414.

Englund, R.A. 1999. The impacts of introduced poeciliid fish and Odonata on the endemic Megalagrion (Odonata) damselflies of Oahu Island, Hawaii. Journal of Insect Conservation 3:225-243.

Erdsman, D.S. 1984.  Exotic fishes in Puerto Rico. 162-176 in W.R. Courtenay, Jr., and J.R. Stauffer, Jr., eds. Distribution, biology, and management of exotic fishes. The Johns Hopkins University Press, Baltimore, MD.

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Holton, G.D. 1990. A field guide to Montana fishes. Montana Department of Fish, Wildlife and Parks, Helena, MT.

Howells, R.G. 1992. Annotated list of introduced non-native fishes, mollusks, crustaceans and aquatic plants in Texas waters. Texas Parks and Wildlife Department, Management Data Series 78, Austin, TX.

Hubert, W. 1994. Exotic fish. 158-174 in T.L. Parrish, and S.H. Anderson, eds. Exotic species manual. Wyoming Game and Fish Department, Laramie, WY.

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Pigg, J., R. Gibbs, and T. Beard. 1996. Observations on two exotic fish species in Oklahoma. Proceedings of the Oklahoma Academy of Sciences 1996: 90.

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Watters, T.G. and S.H. O'Dee. 1998. Metamorphosis of freshwater mussel glochidia (Bivalvia: Unionidae) on amphibians and exotic fishes. American Midland Naturalist.139: 49-57.

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Williams, J.D., D.P. Jennings, and D.C. Haney. 1992. Exotics in the Indian River Lagoon system. National Biological Survey, Gainesville, FL. Unpublished manuscript.

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Other Resources:
Global Invasive Species Database Factsheet

US Fish and Wildlife Service Ecological Risk Screening Summary for Xiphophorus hellerii

Author: Leo Nico, Pam Fuller, and Matt Neilson

Peer Review Date: 11/14/2012

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.