Effect of various photometric pre-selection criteria on the number and redshift distribution of galaxies in the four mock catalogues. We show four cases: (i) only a detection in I_E is required; (ii) detection is required in all four Euclid bands (I_E, Y_E, J_E, H_E); (iii) detection is required in u and all four of the Euclid bands; and (iv) detection is required in ugriz and all of the Euclid bands. As described in the main text, for all bands we adopt a signal-to-noise detection threshold ≥3.