Field study on the diversity of freshwater fishes was conducted in Ba Nam and Ba Xa communes, Ba To district, Quang Ngai province in 2011 and 2012. Based on the collection, the authors recorded 43 species of 33 genera, 17 families, seven orders from these communes. The most diverse order is Cyprinidae with 27 recorded species (representative of 62.8 percent of the total species number). The authors also identified 14 species (32.55 percent of the total species number) of economic value and six species (or 13.95 percent) are being threatened, comprising five species listed in the IUCN Red List (2012) as globally threatened and one species listed in the Red Data Book of Vietnam (2007) as nationally threatened.