Protein, despite its high cost, is crucial for the growth of mud crabs. To optimize protein efficacy, carbohydrates are used combined. In an attempt to minimize the expensive protein- rich feed and reduce the production costs of crab cultivation, an innovative method has been used, namely the apartment system. Thus, the current study aimed to investigate the effects of various levels of protein and carbohydrate in the feed on the carcass, chemical composition, and RNA/DNA ratio of mud crabs undergoing fattening in an apartment system. This experiment used a completely randomized design (CRD) with five treatments and three replicates consisting of different protein and carbohydrate levels: A (P 60%-C 20%), B (P 50%-C 30%), C (P 40%-C 40%), D (P 30%-C 50%), and E (P 20%-C 60%). The study utilized monosex mud crabs (S. olivacea) with an average weight of 129.59± 0.98 grams. A total of 150 crabs were placed individually in crab boxes measuring 40 x 36 x 16cm³ at a feeding rate of 5% body weight, and the feeding frequency was two times/day over a period of 60 days. The results showed that the levels of protein and carbohydrate feed had a significant effect (P< 0.05) on the protein content, meat carcass, and RNA/DNA ratio of mud crabs, but had no significant effect (P> 0.05) on the levels of fat, crude fiber, and nitrogen free extract (NFE) mud crab. Protein and carbohydrates levels of 40% produced the highest values ​​for protein content (68.25%), meat carcass (51.25%), and RNA/DNA ratio (1.52ng/nµL) of the mud crabs. Other ranges of body chemical composition values ​​for mud crabs include fat content (14.10- 15.92%), crude fiber (1.16- 1.54%), and NFE (2.11- 2.44%). Thus, protein and carbohydrates levels of 40% in feed can improve the quality of the mud crab meat. Addintional research is required to further explore this topic comprehensively, ideally using a more economical protein source and a more improved filter.