摘要:In Mexico, several species of fishes are being affected by anthropogenic changes in rivers and streams. In order to understand the potential impacts of human activities on Poeciliopsis fasciata, we examined characteristics of the Rio Salado in Puebla, Mexico that were associated with the presence of P. fasciata. Fish were observed in the river in March 2007 and from November 2007 through February 2008, but not from April 2007 through October 2007. The dynamic nature of the R o Salado likely influences the presence of P. fasciata, as evidenced by our finding fish in the study area only during a limited period during the year. The distribution of P. fasciata along the Rio Salado is clearly influenced by factors related to the permanence of water, the chemical nature of the water (salinity, dissolved oxygen), and the presence of vegetation. Our results suggest that the presence of salt factories (“salineras”) along the R o Salado have the potential to influence the presence of P. fasciata, either through changes in water flow or salinity.