Most of the studies in Table 7 are providing higher recommendation values for Met + Cys, except the lower values for Arctic charr (S. alpinus) (Simmons et al., 1999) or the similar for rainbow trout (O. mykiss) (Kim et al., 1992), compared to the own findings for turbot (Table 3.2). Regarding the recommended Met + Cys concentrations provided by NRC (National Research Council) (2011) and in Table 7, salmonids seem to have a lower Met + Cys requirement in protein than most of the other aquaculture finfish species