When you say bottom dwellers are you reffering to a fish that will occupy the lower levels of the tank, or are you looking for a bottom feeder? If you want a bottom feeder then my vote goes for a school of corydoras...they really are funny little fish that are fun to watch. If you are looking for a fish to occupy the lower levels of the tank however, I love SA cichlids for that...a pair of Rams or Apistos would look very nice.