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Xiphophorus Genetic Stock Center

Xiphophorus Genetic Stock Center

 Dedicated to the Poeciliid fish genus Xiphophorus.

Xiphophorus is a freshwater fish genus comprised of 26 species. These fishes live in drainages in eastern Mexico, Guatemala, Belize and Honduras, with most of the described species living in Mexico. The taxa make up three groups: the Northern Swordtails, the Southern Swordtails, and the Platyfish.

The purpose of this site is to provide information to both the research community and the general public about the Xiphophorus Genetic Stock Center. As a national resource for research animals, we welcome opportunities to share fish with the research community for further research, development, and application.


The Xiphophorus Genetic Stock Center has operated within the United States since the 1930's making it one of the oldest live animal resource centers worldwide. In 1992, due to the retirement of its past director Dr. Klaus Kallman, the XGSC moved to Texas State University.          

The traditional strength of the Xiphophorus experimental model involves the non-biased assessment of genetic inheritance patterns associated with complex phenotypes within intact animals. The high genetic variability among Xiphophorus species and capability of producing fertile interspecies hybrids allows inheritance of any observable trait to be followed into individual backcross hybrid progeny. The XGSC has served to enhance the resources available to the scientific community and promote this model system in high impact research studies. The XGSC is unique as a national research center, and a true scientific treasure.

Walter, R.B. and S. Kazianis (2001)  "Xiphophorus Interspecies Hybrids as Genetic Models of Induced Neoplasia", J. Inst. for Lab. Animal Res. (ILAR J), National Academy Press, 42(4): 299-322.

Kallman, K.D., Walter, R.B., Morizot, D.C., and S. Kazianis  (2004) " Two new species of Xiphophorus (Poeciliidae), from the Isthmus of Tehuantepec, Oaxaca, Mexico, with a Discussion of the Distribution of the X. clemenciae Clade."  American Museum Novitates, 3441:1-34.

Walter, R.B., Kazianis, S., Hazlewood, L., Johnston, D., Kumar, J. (2005)  "The Xiphophorus Genetic Stock Center."  In: Viviparous Fishes, M. C. Uribe and H. Grier (eds.), New Life Publications (ISBN# 0-9645058-5-1), Homestead, Fl.  PP. 343-350.

Cui, R., Schumer, M., Kruesi, K., Walter, R., Andolfatto, P., and G. Rosenthal (2013) Phylogenomics reveals extensive reticulate evolution in Xiphophorus fishes.  Evolution, 67(8): 216-2179.

Kang Hyoun, J., Schartl,M., Walter, R.B., and A.  Meyer (2013) Comprehensive phylogenetic analyses of all species of swordtails and platies (genus Xiphophorus) uncover a hybrid origin of a swordtail fish, Xiphophorus monticolus.  BMC Evolutionary Biology, 13:25-44.

Recent Publications

Click here for a full list of Recent Publications and Supplementary Materials from Published Works

Waveband specific transcriptional control of select genetic pathways in vertebrate skin (Xiphophorus maculatus)

Ronald B. Walter, Mikki Boswell, Jordan Chang, William T. Boswell, Yuan Lu, Kaela Navarro, Sean M. Walter, Dylan J. Walter, Raquel Salinas, Markita Savage. (2018). BMC Genomics 19:355. DOI 10.1186/s12864-018-4735-5

Molecular genetic analysis of the melanoma regulatory locus in Xiphophorus interspecies hybrids.

Lu, Y., Boswell, M., Boswell, W., Kneitz, S., Hausmann, M., Klotz, B., Regneri, J., Savage, M., Amores, A., Postlethwait, J., Warren, W., Schartl, M., and Walter, R. (2017). Mol Carcinog. 2017 Aug;56(8):1935-1944. doi: 10.1002/mc.22651. Epub 2017 Apr 13.

X. couchianus and X. hellerii genome models provide genomic variation insight among Xiphophorus species

Yingjia Shen, Domitille Chalopin, Tzintzuni Garcia, Mikki Boswell, William Boswell, Sergey A. Shiryev, Richa Agarwala, Jean-Nicolas Volff, John H. Postlethwait, Manfred Schartl, Patrick Minx, Wesley C. Warren and Ronald B. Walter. (2016). BMC Genomics 17:37. DOI 10.1186/s12864-015-2361-z

Whole Body Melanoma Transcriptome Response in Medaka

Manfred Schartl, Yingjia Shen, Katja Maurus, Ronald Walter, Chad Tomlinson, Richard K. Wilson, John Postlethwait, Wesley C. Warren. (2015). PLOS One DOI:10.1371/journal.pone.0143057

XGSC Funding from NIH

Funding to maintain and enhance the XGSC is primarily from the National Institutes of Health (NIH) Office of Research Infrastructure Programs, Division of Comparative Medicine (R24-011120, R. Walter, PI).

Questions and Comments

Questions and/or feedback regarding this webpage should go here; all other inquiries regarding Xiphophorus should be directed to the Stock Center.