[glampka]

Has your water been tested for various parameters & what are the results? You're cycle should be completed by now. If I were you, start out with some inexpensive fish like chromis or clowns. Don't mess with damsels since they'll probably be problems later down the road. There is always the possibility that you have a hitch hiler that came in on the rock & is killing things off. What kind of crabs do you have? Any emeralds? If they're not well fed they will go after fish. After the lights have been off for an hour or so, take a look in the tank to see if anything has come out that could be killing off the fish.