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Xiphophorus Genetic Stock Center

Each of the Xiphophorus genomes have been greatly enhanced by PacBio sequencing and Bionano mapping. To take advantage of the improved genomes, the XGSC configured a platyfish genome hub that is hosted on the UCSC genome browser for genetic data visualization and data mining. See link for details.

The XGSC also configured a gene expression browser link to facilitate data visualization and tracking of genes of interest to determine gene basal expression level through light and dark phases over a 24-hr period.


 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., Lu, Y., Savage, M. (2019) The Xiphophorus Genetic Stock Center. “Genetic Resources of Model Organisms – Strategies for Conservation”, R. Jarret (ed.), CRC Press/Taylor & Francis Publishing, In press.

Franchini, P., Jones, J., Xiong, P., Kneitz, S., Gompert, Z., Warren, W.C., Walter, R.B., Meyer, A., Schartl. M. (2018). Long-term experimental hybridisation results in a heterologous transition and the evolution of a new sex chromosome in swordtail fish, Nature Comm. 9:5136,

Schartl, M., Walter. R.B. (2016). Xiphophorus and Medaka Cancer Models, Advances in Experimental Medicine and Biology: Cancer and Zebrafish Mechanisms, Techniques and Models, D. Langenau (ed.), Springer Publishing, pp527-548, Switzerland,

Lu, Y., Boswell, M., Boswell, W., Kneitz, S., Klotz, B., Regneri, J., Savage, M., Postlethwait, J., Warren, W., Schartl, S., Walter. R.B. (2018). Gene Expression Variation and Parental Allele Inheritance in a Xiphophorus Interspecies Hybridization Model, PLoS Genetics, December 26, 2018,

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.

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.

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.

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. 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.

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.