Yeah, females will only complicate teh matter, as spawning REALLY brings out the aggression in these reasonably peaceful fish. Only time they are meaner is when they have free swimming fry. at that point, they'll kill most of the fish in the tank.
Do you have caves for your kribs? they are cave dwellers and will be very edgy if they don't have a hole to call home.
Former advisor and planted tank geek...life's moved on though.