it is very typical for new fish to pick at live rock before they take other feed. This can be a touchy and aggressive species that needs a lot of room, flow, good water quality and oxygen levels. They are prone to ick and are easily stressed, especially in a smaller system (they like to be the boss of the tank). I see there are plans for a 200 gallon, this is good and about the absolute minimum for a full grown adult IMO. Nori sheets are a good idea, I have had great success in getting picky feeders going with several products but I really like new life spectrum pellets and mysis shrimp. Every fish I have kept in the last several years has started feeding on the nls pettets within a few days and most fish take mysis immediately.