I have added live sand without my tank getting all cloudy. If you don't have to much rock, lower the whole bag of sand in to your tank. Turn you pumps off for a few min. Slit the bag open as wide as practical at the bottom and let the sand gently flow out. The other way is to use some sort of plastic container and slowly lower it in to position and pour it out. This takes longer and is more likely to cloud the water. Add the packet that comes in the bag and it will clear up pretty quickly.
Add some rubble rocks for the jaw fish to build its cave.