The biube isn't suitable for corys, unfortunately. The footprint isn't really big enough (except for pygmy corys, maybe
), and if you still have the ceramic media, that is far too sharp for corys and most other bottom-dwelling fish. There is a forum dedicated to biube and biorb owners - I'm sure a Google search will bring it up, I don't want to give the URL here in case anyone thinks I'm trying to poach members or something LOL You can PM me if you want more info.
Shoals of small fish tend to work best, from what I have seen - the rasboras and tetras already mentioned would work well.
Just remember that some fish like to be kept in groups
Oh, and do read the cycling links already given - they are very useful