Oscars usually lay their eggs on a flat stone. If a suitable surface is not provided they may dig down to the bare bottom of the tank and lay eggs on the glass: one big patch of eggs rather neatly organized, each egg affixed to the surface, never on top of one another. The female makes a pass, laying several eggs and the male follows, fertilizing them. If the eggs are fertile, they will usually stay light brown in color, translucent. If they are infertile they will always turn white with fungus. If water condtions are unsuitable (dirty water, wrong pH, too hard) the eggs may get fertilized, but fail to develop and fungus anyway.
Before you fault either of these fish, your friend should check the water in this tank to make sure it is suitable for breeding oscars. Oscars can live in a pretty wide range of water conditions, but in order to breed them, you may need to come up with water that is closer to what oscars are used to in the wild: softer and more acidic (or at least neutral) conditions. Oscars are not the easiest or most difficult cichlids to breed, but your friend can't simply expect young fish. Or your friend may not have been keeping up with his weekly maintenance and the water is very high in nitrate. So have him check on the water for quality and chemistry to make sure it's clean enough, soft enough, acidic enough.
As I said, a couple things could be going on with these particular fish. These are some possibilities: 1. Your friend doesn't have a true pair
. He has two females, which, even though they are mimicking the breeding ritual, the eggs are infertile. Solution: get a male. 2. Your friend has a young pair
. They female is laying eggs, but the male is not yet producing sperm. He passes over the eggs to fertilize them, but he is not yet mature enough. Solution: wait. Let the pair spawn a few more times. Maybe he will start fertilizing the eggs and they will turn into model parents. 3. The male is plenty mature enough, but is sterile:
he is not producing any sperm at all he never will and no spawning ever results in fertile eggs. Solution: get a different male.
The eggs should hatch in 3-4 days; the parents tend them and guard them, then after hatching, usually move the whole bunch of them to a pit dug in the gravel. The baby fish are called 'wrigglers' at this stage. They do not swim, and they are absorbing their yolk sacs. After another few days, the fry begin to swim, the parents continue to guard them, shepherding them around the tank, and you provide some food for them to eat.
Some pairs raise their spawns well, others will always eat the eggs. This is why some breeders choose to rise the eggs apart from the parents. It doesn't matter if the eggs are fertile or not if the fish won't stop eating them!