Colour (g − r) distribution of GC candidates within R_e, GC of NGC 5018 (left) and in the elliptical over-density region (right) after annular and random background subtraction (shown in red and green histograms, respectively). The grey dashed histogram (with arbitrary normalisation, to get a similar scale) represents the spectroscopically confirmed GCs in NGC 1399 (left) and in the entire Fornax cluster (right) from the FDS data (Cantiello et al. 2020).