How long ago did they lay the eggs? I do not know much about breeding fish but here is what I found online about breeding oscars. I hope this helps. According to this site they should be protecting the eggs, not eating them. Good luck!
Fantails and Betas
" As she produces the eggs on the rock she will move out the way and the male Oscar will swim across the eggs and fertilise them. They will continue to do this until she has laid all of the eggs which might shock you at first. They can produce well over 1000 eggs in one hatch. Once the eggs are on the rock the male will take more of a role. He will hover over the eggs and fan them with his pectoral fins. This is to oxygenate them.
He will also become very protective and aggressive. Any fish that dares to go near the eggs can expect a very hostel reception and more than likely will receive a good hiding.
The eggs normally take from 24 to 36 hours to hatch. When they do hatch they will stay attached to the rock for a short while, when the fry detach themselves from the rock, they will probably a lay around the gravel for a short time before becoming free swimming. They will also have a yoke sack attached to them, you will not have to feed them for at least four days. Once the yoke sack has disappeared it is probably time for you to think about putting the fry in a tank or on their own. Oscars are known for being very good parents and will protect their fry by herding them into their mouths. you could leave the fry in with their parents but you will always run the risk of them being eaten as this would happen in the wild. if you want to transfer the fry you are probably going to need a minimum of 30 UK gallons on standby. The reason for this is it is feasible that you will have over 500 young Oscars.
Once the fry are in the tank on their own you will need to do a 20% water change every day as the water needs to be in tiptop condition. You can feed your Fry on brine shrimp; flake or whatever your local fish shop has available for young fry.
If you feed the fried primarily on brine shrimp, they should be around 1 1/2 to 2 inches within three months. If you have a lot of babies, you really only have two options. You can either get yourself an extremely large tank, or you can find a home for the new babies."
http://www.wheelchairanglingandhamradio.co.uk/breeding.html
