Yeah I didn't look at the shape of the tank. Mine is a 40 gallon long (makes it a 4 foot tank), with 4 Africans, and 20 convicts (which are a mix of fry and adults, I have 3 full grown and the rest are about an inch/ inch an a half or under). And I have a emperor 400 filter with biowheels, I do about a 40% water changes. I haven't had a problem yet.
Now before anyone bashes, I'm trying to get rid of the majority of the convicts, everyone but "big pappa". He's my favourite.