保育: The Choy river (about 5 m wide) has a large shaded flow that is born at "Nacimiento de Tamuin" (previously known as Nacimiento de Taninul) spring and runs partly inside pristine terrains owned by the local society of cane growers, whom allow access to the spring some days a week for a fee. the rest of the river before it gets to the town of Tamuin [San Luis Potosi] and merges the Tampaon River runs mostly through private cattle growing lands for about ten kilometers. Apparently due to pollution, some species, like Xiphophorus nigrensis are just found in the upper part of the river.