An individual of Oncorhynchus mykiss (Rainbow Trout) was collected in a diversion canal of the Mississippi River known as Davis Pond located at river kilometer (RKM) 191.03 in St. Charles Parish near Luling, LA. This locality is the southern-most record for Rainbow Trout in the Mississippi River Basin and represents a range extension of 733.5 RKM south from the previous southern-most locality at Lake Whittington, Bolivar County, MS. The collection we report here also represents the first documented record of Rainbow Trout in Louisiana.