HI deficiency in groups : what can we learn from Eridanus
  The HI content of the Eridanus group of galaxies is studied using the GMRT observations and the HIPASS data. A significant HI deficiency up to a factor of 2-3 is observed in galaxies in the Eridanus group. The deficiency is found to be directly correlated with the projected galaxy density and inversely correlated with the line-of-sight radial velocity. It is suggested that the HI deficiency is due to tidal interactions. An important implication is that significant evolution of galaxies can take place in a group environment. 
A. Omar