As a general rule, my cichlids respond very well to a variety of quality foods (flake, frozen, freeze dried, live), and lots of it, heavy filtration, and lots of water changes. This is my regimen for growing them out and getting them to spawn. Some folks like to drop the temp a few degrees for the new water as they are changing it. Kribs and firemouths generally don't need excessive inducement to spawn. My assumption, however, is that you have them in separate tanks.