Do you plan on doing a cool-down period? If you do it will definitely limit your choices of tankmates. I have read that balzanii, being the northernmost ranging Gymnogeophagus, don't necessarily need one.
Well, they recommend a cool-down period for all Gymnogeophagus to simulate winter. I have a few Gymnos in my eartheater tank (3 balzanii, 1 australis, and 1 meridionalis). I asked, because frankly, I can't imagine catching the fish on a yearly basis to remove them to a cool-down tank. I am curious how many people do cool them down and how many keep them year-round at tropical temperature.
You need to cool gymnos down to get them to breed but I do not believe they need it to live. I've heard for a couple of years now that they can "burnout" if you dont cool them down, but I have yet to see proof or know what exactly happens when they burnout. I keep all my gymnos in unheated tanks mainly cuz you can, plus saves me some money.
well in that case ill prob do a cool down at some point if the fish look unhealthy. any other good gymno species i could throw in? again its a 55 gal tank..