Mangrove crab Scylla serrata is associated with mangroves throughout the Indian and Pacific oceans. This species is crucial to aquaculture and fishing. As wild stocks decline and demand rises, mangrove crab aquaculture has become increasingly popular. However, feed development research and its quality are still meager in the industry. This study examined the interactive effects of different levels of crab shellmeal (CSM) to fishmeal (FM) replacement on proximate composition, feed utilization, carcass composition, growth, and survival performance of mangrove crab S. serrata. Four formulated diets were prepared, and one for chopped trash fish (TF) supplement: 30% FM and 0% CSM (Diet 1) as a negative control, 20% FM and 10% CSM (Diet 2), 10% FM and 20% CSM (Diet 3), 0% FM and 30% CSM (Diet 4), and TF as a positive control (Diet 5). Experiments were conducted in each group for 30 days with ten replicates. Results revealed that formulated diets using different levels of CSM and FM did not significantly affect mangrove crabs' growth and survival rates as well as feed utilization. However, the proximate composition of Diet 4 was significantly higher among other experimental diets. Moreover, the crab's whole body composition (ash, moisture, carbohydrates, crude protein, crude fat, and calories) with different levels of CSM and FM was significantly improved. Hence, it is possible to enhance the carcass composition and proximate composition by supplementing CSM; however, it has no effect on feed utilization, as well as the growth and survival rates of mangrove crab S. serrata.