Based on the materials from a longline survey carried out in 2013 in the Weddell Sea, the bathymetric distribution of the Antarctic toothfish Dissostichus mawsoni, its size/weight and age composition, the maturity degree of its gonads, and its nutrition are analyzed. Individuals with a length of 63–170 cm and a weight of 3–59 kg, aged from 6 to 32 years, are recorded in the surveyed range of depths (786–1552 m). Compared with other Antarctic seas, small Antarctic toothfish (with a length of up to 70 cm) occur at deeper layers. The weight of large fish in the Weddell Sea (>100 cm) is lower than that of the individuals with the same size in the Ross Sea. It is assumed that this is due to a lower abundance and diversity of items of nutrition (four vs. ten fish species).