i think the level of aggresion between aros will always be there, however, it's true that silvers are not hostile to the other tankmates..
if your silver gets along with other aros, you're lucky, it does not happen all the time..
than again, maybe it's the other way round, if your silver is hostile towards other aros than you're one unlucky :lipsseale
Mine just started tearing up the other two in the tank..(3 silvers altogether)