Mud crab (Scylla serrata) is a high-value fishery commodity, but the success of its culture is still influenced by growth and moulting processes. This study aimed to analyze the effects of different rearing substrates on the growth rate, moulting frequency, and moulting time of mud crab. The study was conducted at the Dakota Crab Culture Facility, Mataram City, and the Aquaculture Environment Laboratory, Aquaculture Study Program, University of Mataram. An experimental method was used with two treatments, namely P1, a beach sand substrate, and P2, a beach sand substrate with the addition of mangrove leaves. Rearing was carried out in crab boxes connected to a Recirculating Aquaculture System (RAS). The main parameters included moulting frequency, moulting time, absolute weight gain, absolute length growth, Specific Growth Rate (SGR), and Survival Rate (SR). The data were analyzed using a twosample t-test assuming unequal variances at the 5% level. The results showed that substrate differences had no significant effect on any parameter (p>0.05). Descriptively, treatment P2 produced a higher moulting frequency of 0.500±0.534 times/day than P1 at 0.375±0.517 times/day. Moulting time in P2 was also slightly faster, at 38.00±16.4 days, whereas P1 was 39.67±11.3 days. Thus, the combination of beach sand and mangrove leaves tended to be better for moulting frequency and moulting time, but the differences were not statistically significant. Keywords: Growth; Mangrove Leaves; Moulting; Moulting Time; Mud Crab; Substrate