If it's a somewhat small rock, yeah, you can. Just put it in the fry tank and black that out. If they are wanting to hatch, they will. Check with a small flashlight in an hour or so if they've hatched.
I'd put an airline in the corner of the tank also. Get a little flow in the tank, just not a lot.
I'd put an airline in the corner of the tank also. Get a little flow in the tank, just not a lot.