hhhmmm.....when you say minnows, are you reffering to white cloud mountain minnows?? If so, I may warn you that at times they tend to combat a bit with neons. As for wanting to add cichlids to your tank, you are pretty limited there. I would think maybe some rams, but use caution. As for kribs, they are great fish, but when the mature a bit and get ready to spawn, your neons are history. I think perhaps you would be better served sticking to regular tropicals for your 15g tank, and perhaps look into a 29g to start a small cichlid tank with. For the most part, tropicals and cichlids don't mix well.
"J"