H. cynogutalatus (Texas) can take cooler temps, A. rivulatus is from northern S. America, it is totally tropical, All the species of cichlids from Southern Uruguay and Argentina can take temps down to 40F, it commonly freezes there. I froze my ass off the first 3 days we were there on my first trip and then it watrmed up, we go down in December which is early Spring in the southern Hemisphere. Many Gymos can be keep outside year round along the Gulf Coast and the West Coast here in the USA. Best place to find out more about these fish is Felipe's web site.
http://www.aqvaterra.com/
I just don't put a heater in the tank and let it fluctuate with the seasons. All my Ururguay fish are breeding right now.