I currently have two female paradise fish in my 20G unheated tank. As they're both female they don't seem to fight too much, they do chase each other occasionally but mostly they keep to themselves. I am wondering if there is anything I could add to the tank? It's semi-planted (I'm slowly replacing my fake plants with real ones as I get more confident) with not too much of a current to keep the Paradise fish happy but I do have an oxygen pump even though the Paradise fish don't necessarily require it. I'd ideally like to add two or three smaller fish, but not too small that they might get bullied by the Paradise's. Any recommendations? Or is it best to keep them alone? They're around 2 inches at the moment.