Trichodina mutabilis (Protozoa: Ciliophora: Trichodinidae) from the characid fish Astyanax mexicanus in the Cuatro Ciénegas region, northern Mexico

As a part of a series of ongoing studies on trichodinids of freshwater fishes of Mexico, several species fromdiverse localities in the Cuatro Cienegas region, Coahuila, northern Mexico, were examined. Wet smears of gills andskin were made fresh and screened for the presence of trichodinids under light microscopy. Additional specimenswere fixed for SEM. The only trichodinid species found was Trichodina mutabilis, a parasite of the characid fishAstyanax mexicanus. This ciliate protozoan has been introduced from Asia to many countries, including Mexico, withits original host, the Asian carps. The present record is the first for Mexico and the second in North America, beingthe first record of a Trichodina species for native wild freshwater fish in a natural environment in Mexico, since allprevious records were from exotic cultured fishes.