hollyp0p
Fish Herder
just to say, my tank is about 14.5 gallons and I had tetra in there (neons) and they were fine, they had to go unfortunately back to lfs due to fin nipping.
So basically depending on what fish you have the inch per gallon rule might give or take a few. If you have plecos or snails, doesn't really take into play since they stick to the glass out of the way anyways.