Edit: It's not really a good idea to add fish or change things around in a tank just before you go away. Get them when you get back. If they die while you're away, they could wipe out the rest of the tank.
I think some more cories would be good. Three is the minimum number you should keep, but the more you have, the more fun they are
By the way, could you post a link to your 30g thread so people don't have to search for it?
