The marbled rockcod (Notothenia rossii) is a species of marine ray-finned fish, belonging to the family Nototheniidae, the notothens or cod icefishes.

[2] The marbled rockcod was first formally described in 1844 by the Scottish naval surgeon, naturalist and Arctic explorer John Richardson with no type locality given, although it is thought likely to be Kerguelen Island.

[3] Richardson gave it the specific name rossii which honours James Clark Ross, the leader of the Ross expedition, a scientific expedition by the vessels HMS Erebus and HMS Terror to survey and explore the coasts of Antarctica.

Spawning takes place once a year and the young fish stay mostly in shallow water in the fiords and bays, feeding mainly on zooplankton.

[2] The marbled rockcod was heavily fished by Soviet fishers during the 1960s and 1970s, with catches exceeding 100,000 tonnes in some seasons; it almost disappeared from around South Georgia Island, and by 1980, was depleted throughout the Southern Ocean.