Lumi-lumi fish (Harpodon nehereus), often known as Bombay duck, is a species of demersal fish that is commercially significant in Meulaboh, Aceh. This species can survive the entire year. This fish is abundantly available, although it is frequently not utilized properly. It is exclusively traditionally processed. It has been observed that Lumi-lumi has a high nutritional value. This study aimed to determine the nutritional composition of fish in Lumi-lumi. In this study, Lumi-lumi fish were divided into two groups: those that were steamed and those that were not. The nutritional composition of fish that had been converted into flour was determined. In this investigation, the yield of Lumi-lumi fish flour was 10.23% in the non-steamed condition and 10.57% in the steamed condition. The nutritional value of steamed Lumi-Lumi fish flour protein was significantly (p<0.05) higher than that of unsteamed Lumi-Lumi fish flour protein, 13.32 ± 0.48% versus 9.50 ± 0.70%, respectively. However, the fat content of the steamed treatment was 12.56 ± 1.18%, whereas the fat content of the non-steamed treatment was 14.24 ± 0.96%. The steam treatment significantly (p<0.05) reduced moisture and ash content compared to the non-steam treatment. In contrast, the fiber content was significantly (p<0.05) higher after steaming. Therefore, the protein content of steamed Lumi-lumi fish is greater than that of non-steamed Lumi-lumi fish, and the fat content conforms to SNI 01-2715-1996 fish flour quality specifications.