HAH! That's exactly the sort of tank I'd have in mind. (I've always dreamed of an African community with a school of elephant nose but this tank won't cut it for them!)
Do you think if a ctenopoma and African knife were bought young and added at the same time they'd be more tolerant? I was actually giving up hope on all this until I saw your tank!
Those congos are huge! I think I'd want to trade them off for something else, but don't know what, especially if I was keeping it African. An actual school would be nice but it need to be pretty large for these other guys. My mind draws a blank for other African fish that would be good. I know there's those yellow tail tetra but they are just dull congos from what I can tell.
Otherwise I may just go with Kribensis
or some other dwarf African cichlids.
Instead of a featherfin, I was thinking a Hoplo Catfish
if I can find one.. Otherwise the synodontis are all African and suitable, correct? I love big whiskers on catfish, and I'm totally fine with rarely seeing the fish as well. Maybe if I can train it to eat earth worms out of my hand, that'd be awesome.
And I love African butterflies so that's another bonus, they are like $20 each here though so they may be a later addition.