The taxonomic composition of the fishes obtained from mesopelagic RMT-8 hauls, which were deployed during cruise MD-42/SIBEX-II of R.V. Marion Dufresne, and of lanternfishes sampled by French research vessels and commercial trawlers operating in the western Indian and eastern Atlantic sectors of the Southern Ocean, is reported. Protomyctophum (Protomyctophum) choriodon (fam. Myctophidae) and Benthalbella macropinna (fam. Scopelarchidae) represent new records for the Indian sector of the Southern Ocean. There is no evidence of zonal distribution patterning in species found south of the Antarctic Polar Front, although a northerly spread of epipelagic East wind Drift species may occur between 65°E and 75°E, in association with northerly transport in this region. Myctophid species assemblages are similar in the Indian and Atlantic sectors of the Southern Ocean, with no indication of population structuring within the two sectors. Analysis of lanternfishes from the stomach confirms the vertical migratory feeding behaviour of Champsocephalus gunnari and suggests predation confined to the epibenthic layer for Dissostichus eleginoides.