Here are some cold water cichlids, these will tolerate a fairly lengthy amount of time in the cold.
most from the genus Gymnogeophagus (although balzani is a bit more sensitive)
many from the genus Australoheros
some of the pike cichlids, but maybe only those from south of the Brazilian border
I have kept all the above in unheated tanks, where the water temp falls to 50'F without problems, I have also kept them in ponds in Milwaukee where summertime water temps can drop into the 50sF
Although most Central American cichlids will take short drops in temps, anything more than a few days can be fatal.
I tried Cinilichthys bocourti and pearsei in my pond, in July in Milwaukee, and they didn't make it thru a one week minor cool down.