How big is your tank? If it's too small, then that might be why the male went after the female so viciously. If you've got 4, that could make it even worse. When you see 2 start to pair off, take the other 2 back. Then, after they spawn and the eggs hatch, move the parents or the fry to another tank if you want them to have a better chance. It took my kribs 3-4 spawnings before they didn't all die and even now, I've only got 3 fry out of probably 8 spawnings (though I haven't taken any pains to save them).