Advice needed on stocking a 20-30 gallon hex

Hello everyone! I hav some famialily members asking me what kind of African cichlids can they put in this cool looking hexagon tank of theirs. It's small!!! But I have no idea other than mabey some small tanganyikan's! I was thinking maybey getting them interested in south American cichlids maybey a couple of fire mouths or convicts. And some tetras! I'm pretty sure it's a 30 gallon! It used to be my tank, when I started out in the hobby. I used it as a grow out tank for my jag, gt, rt's and salvini. Then tried a salt water. They also have a 120 gallon with a eclipse cat lg pleco, and bala sharks. They use canister filters on all tanks. Any advice would be greatly appreciated!