Abstract: Marine ranching is considered as an efficient tool to protect and restore the coastal fishe-ries resource. In order to assess the ecological impacts of the construction of marine ranching on rocky fishes, the feeding habits of Sebastiscus marmoratus collected at the marine ranching area off Ma’an Archipelago were studied using stomach contents analyses and stable isotope analyses. Results showed that S. marmoratus mainly preyed on amphipoda, crabs and cephalopods before the construction of marine ranching. The dominant prey species were Caprella sp., Loligo japonica, Charybdis japonica, Petrolisthes japonicas and Amphiura vadicola. Proportion of crabs in the diet of S. marmoratus increased with the increase of fish size, whereas the proportion of amphipoda decreased. After the construction of marine ranching, S. marmoratus fed mainly on crabs, amphipoda, and fishes. The dominant prey species were C. bimaculata, C. japonica, Caprella sp. and Thryssa kammalensis. Proportions of fishes and crabs in the diet of S. marmoratus increased with the increase of fish size, whereas the proportion of amphipoda increased and then decreased. Results of the stable isotope analyses suggested that S. marmoratus populations in the marine ranching area off Ma’an Archipelago could be divided into three feeding groups based on size variations: <10.0 cm BL, 10.0-14.0 cm BL, and ≥14.0 cm BL. The mean trophic level of S. marmoratus was estimated as 3.40.