The stocks of Dissostichus mawsoni in the Division 58.4.1 were vulnerable with a big range of about 1,000-2,000 t per SSRU in Division 58.4.1. However, there is not enough data and information to assess the robust stocks and deliberate proper measurements for sustainable utilize, especially relate to diet and feeding strategy which may lead to think about ecosystem based stock assessments and fishery managements. Therefore, the Korean scientists analyze diet composition and feeding strategy of Antarctic toothfish, Dissostichus mawsoni in SSRU 58.4.1.C-a as a part of Korean research plan for the exploratory longline fishery for Dissostichus spp. in SSRUs of 58.4.1 C and E during 2012/2013 season. This study was carried out based on the results of stomach content identification of the Antarctic toothfish caught in SSRU 58.4.1 C-a in CCAMLR Conversion Area in March, 2013. The diet composition and feeding strategy of Dissostichus mawsoni were studied using 36 specimens (104 to 176 cm in total length). D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes, especially Macrourus whitsoni with 14.72% of the diet by weight. Its diet also included small quantities of mollusks, crustaceans, and seeweeds. In this study, fishes were the dominant prey item in all size classes (I, 104-140 cm TL, and II, 140-176 cm TL). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes and showed narrow niche width.