first question is how are you cycling your tank? do you have live rock in there? you have to cycle the tank first b4 you really want to add fish. cycling means taking your tank thru the nitrogen cycle where waste is created, then ammonia rises, then nitrite rises, and after both of these come down you will start to accumate nitrate. this process usually takes about 4-6 weeks, but you have to start it with something that will decay in the tank like a cocktail shrimp. some people do use damsels but sometimes at the risk of the fish dying. do a search on this site and put in cycling a tank. you should get alot of info to help you out. good luck