Here, we provide diagnostic plots for the 2021 assessment for Ross Sea region Antarctic toothfish (Dissostichus mawsoni) presented in Grüss et al. (2021a), following the recommendations of WG-SAM-2015 (SC-CAMLR-XXXIV 2015 Annex 5). The stock assessment is described in Grüss et al. (2021a), and a detailed description of the stock area, stock assessment methods and the stock assessment parameters is given in Grüss et al. (2021b).