The grey rockcod feeds mainly on macrozooplankton and is of minor importance to commercial fisheries.

The grey rockcod was first formally described in 1880 as Notothenia squamifrons by the German-born British ichthyologist Albert Günther with the type locality given as Kerguelen Island.

[1] The colour of the body is greyish above marked with 9 non-uniform, wide, dark bars that join on the underside.

[1] The grey rockcod is the dominant fish species in the waters off the Kerguelen Islands, which is where the greatest plankton productivity in the Southern Ocean takes place, and this population has one of the fastest rates of growth.

These fish reach sexual maturity at lengths of 34–36 cm (13–14 in) at ages of 8 or 9 years old, faster than any other population which has been studied.

[5] Spawning occurs at the end of October in the Kerguelen and Crozet islands while in South Georgia it happens in February.

[5] This species feeds mainly on larger zooplankton, mostly crustaceans, cnidarians and salps, as well as fishes found in the water column.

In the Kerguelen Islands only the marbled rockcod (Notothenia rossii) and the mackerel icefish (Champsocephalus gunnari) are a more important catch than this species.