Gulamah fish (Johnius belangerii) is one type of marine fish found in Dumai waters. The study aimed to analyze the composition of natural feed on the stomach contents of gulamah fish obtained in Dumai. Research methods are survey methods, sampling is done by purposive sampling. The study was conducted in April-June 2022. Gulamah fish samples collected were 60 fish (in West Dumai Subdistrict 30 fish and East Dumai Subdistrict 30 fish). Fish samples were divided into 3 size classes, namely 3.1-8.3 cm; 8.4-13.5 cm and 13.6-18.7 cm. The results showed that the composition of food in the stomach contents of gulamah fish obtained in West Dumai Subdistrict is the size of class I (detritus IP 50%; and fish IP 50%), Class II (detritus IP 64%; fish IP 17.8%; shrimp IP 13.4%; and shellfish IP 4.8%) and Class III (detritus IP 5.6%; fish IP 83%; shrimp IP 5.6%; and shellfish IP 5.9%). The composition of food on the stomach contents of fish obtained in East Dumai Subdistrict consists of class I Size (detritus IP 57%; fish IP 10%; and shrimp IP 33%); Class II (empty stomach contents); and Class III (shrimp IP 100%). This indicates that gulamah fish (J. belangerii) is classified as a carnivorous fish.