Make sure whatever they decide to lay on has a lot of flow going over it, like put an airstone so that the rising bubbles travel over the surface of the eggs. Once they start free swimming feed them some of that liquid fry food that Diacks sell or get some baby brine shrimp or microworms. Water changes everyday, I done about 25% without any problems.
Though that same pair had no problems raising the fry until they were free swimming then I removed them as there was too many fry and made it easier doing frequent water changes.