I've got some Geophagus Balzani in a 75 and would like a couple of dithers just to add to the tank. I don't use a heater at all cause the Balzani likes cold water. What are some good active dithers that don't get too big and can take the cold water?
A bluegill or creek chub would be good, if you don't mind going fishing a bit. Both will take worms. Both are fast and aggressive enough to hold their own in a cichlid tank, but not too aggressive.
If you're just looking for dithers, shiners and dace are what you're looking for. If you can take a seine net out, that's great. A cast net can do some damage to what it catches, but I've kept some fish from one. A dip net is another option. Just go out and see what you get.
Dace are minnows like shiners; just another name. They are both schooling fish and easy to find in rivers and streams. What city in Tenn. do you live in? I could look up the drainage and tell you what kind of fish are near you. If you want something large, you'll probably want some Cyprinella sp. or something.