Bottomfeeder: Well, I guess so...I really meant human response, though. The lack of clarity is my fault. I have some Characins right now, and they kinda suck... they only school and eat

I really prefer a single specimen fish, but I know it's hard for a 20gal. Thanks for your help!
Will: I'm not that into dwarf cichlids, but I had rams before. Then I got bored of them and changed my tank, haha. No offense to dwarf cich fans, though.
Lupin: I definitely agree that they're cool interesting, I've had (much smaller) ones before...maybe I could have one in there with a centerpiece fish?
importracer: Convicts sound like a great idea! Space isn't an issue, though. I have my terrarium, empty 20g and 10g guppy tank on the bay window in the living room and my newts and bettas are in my room, on my bookshelf

I still have the other bay window in my room, so I guess I have a good deal of space. Any fry that appear could be fed to my newts and turtles. A downside of convicts are that although they have good human response, they are a bit on the ordinary side...
synodontisjack: Puffers are a good idea, what are some of my choices? I don't really want GSP's or F8P's though. They seem too ordinary. Spiny eels spend their days either all holed up or under their substrate, so I think it's not a good choice. I don't really like avocado puffers either...I've seen some brownish, rough skinned puffers with red eyes, what are those called?
sour_girl: I've never actually had cichlid fry, but I think I'd actually want them, so that I can finally say I've had that experience (not that convicts are a feat) and the fry are certainly useful as live food for my other fish or as an income generator.
mcsx: Hmmm...I was considering shelldwellers before but I really think they would get a bit tedious for me after a while...I don't have the tank for Malawis, but I'm not really a fan of shellies....
Thanks everyone!
My new options:
Convicts
Puffer
(Plus of course, the Apple snail)
Are the following fish possibilities?
African Butterfly Fish
Maybe paradise fish or large gouramis?
I'm really liking the convict idea right now....maybe I could get a pack of feeder convict fry and grow them out and select the best pair?