aggressives in a 20... Lamprologus ocellatus! hehe
a 20 doesn't provide much room for anything that's aggressive. If it was a bit bigger I would suggest convicts.... *shrug*
those Ctenopoma look crazy! I've never even heard of em before... african labyrinth fishes? sweet hehe
as far as your 46 gallon, when you list it in your sig like that, you're just asking for it on these boards
If you say they're doing fine, I believe you. Given the right filtration and enough water changes, lot's can be done that people here wouldn't recommend.