Location of intrinsic (grey contour lines) and dust-attenuated, but not flux-limited (blue contours) GAEA-LC galaxy populations in the Hα (top row), [N II] (second row), Hβ (third row), and [O III] (bottom row) line flux-stellar mass plane at different redshift ranges, following their observability with Euclid’s grisms given the line’s wavelength (different columns as indicated by the legend). Overplotted are the flux limits of the blue and red grisms in the Deep Survey mode (EDS, blue and red dashed lines), and the red grism in the Wide Survey mode (EWS, yellow dash-dotted lines). Grey panels mark GAEA’s resolution limit of stellar masses below 10⁹ M_⊙. Percentages indicate the observable fractions of the resolved sample above 10⁹ M_⊙ when applying the EWS or EDS limit to the dust-attenuated emission-line fluxes (unattenuated fluxes in parentheses, colours reflecting survey mode and grism).