It will be tough, to be honest, to have a reef safe seastar. Brittlestars and serpentstars would be fine. Reef safe seastars a bit marginal. Definitely not a blue Linckia, and I would avoid a Fromia as well (don't let the small size fool you... these "red bali stars" are tough to keep longer than 18 months in smaller tanks). You could maybe consider an orange, but it is on the cusp, IMO. If you could find a Linckia multiflora - the mottled Linckia, that would be a decent shot. What are your parameters, and is it a reef tank?