Parapocryptes serperaster inhabited along the muddy flats of rivers, coastlines and estuaries in Mekong Delta. It was also a commercial fish and could aquaculture in the future in this area. However, there is little known about this goby, especially its food composition which could be one of the most important factor used for future aquaculture. The preliminary result of the food items in its gut was studied from August to December 2012 in 30/4 spring, Nha Mat, Bac Lieu city, Bac Lieu, Vietnam. After collecting, specimens were brought into the Laboratory of Animal, Department of Biology, School of Education, Can Tho University to identify food items in their guts. The result showed that it RLG was 2,16 +/- 0,6, which indicated that this goby belonged to herbivorous fishes.