mmmmmmmmmm upside down catfish now they are cool. I warn you the species that you must purchase are Synodontis Nigriventis they reach about 3inces and swim mostly upside down. However when buying these guys shops often get imposters which get much bigger, a common one i keep getting at my local store is synodontis eupterus or the feather fin catfish.
Upside downs like lots of cover and are mostly nocturnal, their natural diet is bugs so blood worm is accepted readily however my three like agae tablets as well. I would say that three is the bare minimum but i am considering buying more as they are shoaling fish!
Banjos i am not so lucky with but i have one survivor out of ten (eeeeeeeep!) but he adores blood worm and protein pellets. He's shy and likes to dig and is mostly nocturnal, give him some cover at the front of the tank and he MAY set up home there mine has and it keeps him out of direct tank light and the loaches!
Buy these guys as they are soooooo cute!