This actually might not be a bad thing at all, fish that hang out at the top of a fish tank are sometimes due to a lack of oxygen in the water. If your goldfish is hanging out by the rocks, and scratching the bottom of the tank (gravel) then it might be a chemical inbalance in your water. If this is the case, either buy a water test kit from a pet store, or find a store that will check your water for free. Hope this helps :)