There are so many peaceful cichlid in SA, so it’s hard to say keyhole is the most peaceful, but is likely in the top five for SA.Hi,in the aspect of European aquaristics, it is the most peaceful fish for me Cleithracara maronii .
There are many nasty cichlid in CA and few, if any, are considered peaceful. Rainbow is on the milder end on CA standard, but above SA. Not all convicts are nasty as there are milder convicts such as HRP, nanoleutus, cutteri, if you include non Amatitlania species.Rainbow cichlids are considered to be on the milder end for Centrals. I would say yes and no. They don't fight for fucs sake like Convicts, but they can get nasty if the mood hits. I had one that intimidated a large syno Catfish by popping it on the head relentlessly. The fish eventually worked it out.