Hi bluejohanni: I have some danios in with my kribs now and they get along pretty well. I'd be a little more worried about your sun cat, though, especially in a small tank. Kribs are territorial and can get aggressive with any bottom dwellers that come into their territory. Sun cats can get pretty big, too, so in a small tank that could be a problem as well. You might want to look into some other fish instead of the kribs, given your setup.
the sun cat will out grow everything im your tank very very fast and eat the lot. Talking from personal experience. I seen mine 6 1/2" eating a 5" silver shark it had it half in its mouth head first and was ramming it against the side of the tank to force it in.