The opinion of experts differ, but dwarfs should be kept in pairs (1 male to 1 female) in a tank no smaller than 15 gallons.
These fish aren't suitable for a 5 gallon tank, though.
FireOasis - 3g
Zachary the Halfmoon Plakat
CichlidHaven - 55g (under construction!)
0.0.7 Black Widow Tetra
1.0.1 Convict Cichlid
0.1.0 Firemouth Cichlid
HermitBase - 10g
Zephus & Monoculus the Purple Pinchers (Coenobita clypeatus)
x1 Convict Cichlid Pair (actively breeding)