Congo tetras are cool but if I were you I would go with Buenos Aires tetras as it keeps with the SA theme, as for bottom dwellers I would do a group of pictus or hoplo catfishAwesome tank!! Ive been looking at congo tetras for a while and if I go this route can they work for dithers (maybe a school of 12 or so). Then adding the BGK, Threadfin acara, Sevrum pair, pink tail chalceus, than maybe some other dithers and bottom dwellers?