I currently have a 20 gallon wide freshwater tank with bunch of rocks and fun hiding places... I've got a dwarf puffer fish which has been doing fantastic for several months (turns out they aren't brackish only!), as well as a 2inch pleco, a tiny dwarf African frog, and an electric yellow African cichlid (which I understand might not be the best choice).
I'm looking to add more fish, and haven't figured out which would fit well. I understand the cichlid might be aggressive if I don't combine him with other cichlids, but my tank isn't necessarily big enough to do that... I'd like some form of community tank, but wouldn't be opposed to a species tank or, well, anything else actually.
Let me know what you experts think I could be able to add without much problem. My pH is kept around 7.5, and my tank is 78 degrees F. Nitrites, ammonia, etc are all low levels, and I've no idea what my water hardness is [nor how to find out, actually. I get my water from my dorm room tap and I dechlorinize it].
Thanks for your thoughts.