An analysis and summary of extensive published and unpublished data on size-weight and size-age composition of South Georgia mackerel icefish (Champsocephalus gunnari) for 1965 to 1987 is presented. The results enable the calculation of reliable weight-length equations for males and females by season and the verification of parameters for the Bertalanffy growth equation. Mean value of natural mortality rate was estimated at 0.55.