If your kribs have eggs, the female will hold up in the cave and rarely come out; even for food. This is typical krib behavior, my male will go nuts even attacking my glass magnet. Keep both fish in there, if you are going to move either krib it should be the male (which I don't advise of you plan on keeping the fry). The female cannot defend the fry alone and if you remove her the male is likely to eat the fry.
General rule of thumb, if you are going to remove a fish temporarily due to aggression, it should always be the agressor.
Edit: Before I forget, what is your stocking like? And what size tank?
Hi there,
I have moved the female to the smaller tank and the male has really calmed down. It's a shame because I love having them together, however the larger tank that the male is in is quite heavily stocked and I was not aware of how territorial and aggressive they can be when I got the kribs. Unsurprisingly, the LFS did not give me the best advice (I'd gone to get some assassin snails and they sold me the kribs as they would eat the snails, which they don't do particularly effectively!).
When they did have fry, they were in the tank hanging round by the bogwood, I guess this is as there was no cave for them.
I think my best bet will be to keep them separate until stocking (or another tank!) allows them to be together,
Mark