Estimate of the isolation parameters, local number density η_k,500 and tidal strength Q₅₀₀, for 306 CIG galaxies with at least one neighbour within 1 Mpc and |Δ ν|  ≤ 500 km s^-1 using the spectroscopic data. Upper-limit estimates are depicted by solid grey lines. Colours, according to the legend, correspond to the redshift completeness of each CIG field (the percentage of extended neighbours, down to m_r < 17.7 mag lying within a projected separation of 1 Mpc from the CIG galaxy with a measured redshift).