The goby Eleotris melanosoma is a commercial fish and widely distributed in estuary and river, but little is known about this species especially its food composition. This study was carried out in the coastline in Tran De, Soc Trang for a year-round (6/2016–5/2017) to contribute useful data on digestive tract morphology, food and feeding habit of this goby species. The species is a carnivorous fish feeding mainly on crustaceans (78.78%) since its relative length of the gut was 0.52±0.02 SE based on data analysis of 60 individuals. Besides crustaceans, small fish (10.65%), mollusca (8.66%) and detritus (1.91%) were also found in the fish digestive tract. The food composition of this goby varied with gender and season. However, the fullness and Clark indices of females (159.08±14.85 SE and 0.90±0.03 SE) were nearly to males (183.82±42.11 SE and 1.01±0.05 SE). Likely, fullness index of E. melanosoma in the wet season (177.04±29.81 SE) roughly equalled to the dry season (143.19±24.05 SE). However, the Clark index varied with the season (1.00±0.03 SE for the wet season and 0.75±0.06 SE for the dry season). The results contributed scientific data on nutritional characteristics of this species, which was basis for aquaculture study and sustainable exploitation this goby.