Dwarfs
Fish Connoisseur
IME, adult featherfins will become aggressive with one another, upside down catfish are the ones that like to be in groups. A single featherfin will be enough, I see plenty of mine, the fat swimming garbage cans they are
Also, as for cichlids:
Rainbow cichlids
Firemouths
Geophagus (Brasiliensis and surinamensis are very nice)
Would all do well with your oddities IMO, Those are all semi aggressive and, since none of the other fish are cichlids or cichlid-like (Anabantoid, for example) there shouldn't be major problems on the long run.
Also, as for cichlids:
Rainbow cichlids
Firemouths
Geophagus (Brasiliensis and surinamensis are very nice)
Would all do well with your oddities IMO, Those are all semi aggressive and, since none of the other fish are cichlids or cichlid-like (Anabantoid, for example) there shouldn't be major problems on the long run.