I thought I posted a reply yesterday to this....I'm losing it.
Anyway, like I thought I said yesterday, 5 Africans in a 55g is okay but it will take forever to cycle the tank. Also, Africans do better with a same species male to female ratio of about 4f/1m, that being said, 20-30 fish in that tank would not be to many as long as you stick with fish that wont get over 6"-8". A slightly crowded tank will qwell aggression. Like I thought I said before, watch out for that Auratus, very aggresive, borderline evil. Seriously.
You would be surprised at what fish I have had with Africans. I currently have a 14"Oscar, a 6" Blue Botia loach, a three spined toad fish, a 12"reg pleco and 14"sailfin plec., 5_4"-5" Salveni. These are in with a mixture of 20+ Africans from Malawi, Tanganyika and a couple from some lakes i forgot( I seem to do that lately), all in a 210g. I used to have rocks stacked for caves but have discovered that these fish are just fine with a single rock layer and driftwood over the top to make their caves. People use anything and evrything for caves but dont forget the other fish in the tank. Maybe those fish dont like a lot of caves. The Frontosa I have would rather hang out about mid water colmn, and the Salveni like to chill in the plants. Any armored suckermouth catfish will be fine with Africans, but there could be some tail nipping.
Trial and error is a normal part of fishkeeping. People say Africans should only be with Africans, Amazon with Amazon, etc,etc. In my experience, if you get all the fish as juviniles, pay attention to aggression compatability and introduce them together all at once, you more than likely will succeed.
Just watch that Auratus. Evil.
