John, I've had kribs breed in 10g tanks! Not ideal, but they seemed to think it was OK!
What other fish are in there? Kribs are very shy if they are alone. You'll never see them. Mine became much more active once I added some pearl danios to one tank and white cloud mountain minnows to the other. So yes, they will breed with other fish in the tank.
Make sure they have caves, as both my spawnings have been in caves, not on a flat surface.
don't worry if they seem to take their time about it, it could take months for a pair bond to form, or it could happen as soon as a male is introduced. they are wonderful parents and will guard the nest vigorously, so the other fish MIGHT get stressed out, Oh, and plecos and cory cats are NOT a good idea if you want eggs and fry to survive.