I've just posted this reply a couple of links down.....
My yellow labs spawned in my normal tank which is full of larger cichlids which would normally scoff them up. In addition to rocks, I had planted bogwood in my tank, the fry took cover in there, ignoring the rocks.
I bought a couple of large shells (looked naff but plenty of room for fry to hide inside) and I don't think I lost any!
When they got a bit larger and the other fish lost interest, I got them all out to take to a fish store - I had to strip the tank to do this as there was no way I could catch them with all that cover! Over seventy in all!
So long as they have hiding places, they have a chance.
Good luck!
The fun bit is catching them when they have to go!!!!
We thought we had them all, and still two managed to escape - we kept them in the end - it was the easiest way!