Not Reef Tank Suitable
True starfish/sea stars comprise the Class Asteroidea, and there are about 1600 species encompassing various 'orders and families.' To list the species described here it's necessary to list them in the order 'and' family they occur in to prevent their genera from simply becoming alphabetically listed.
Keep in mind that only a few are truly suited for the aquarium. They can be found to depths of 20,000 feet and the majority of starfishes, now more properly referred to as sea stars, are carnivorous or omnivorous and can eat small fishes, algae, mollusks and coral polyps. In fact, they don't have to fit their prey into their mouth, as they are capable of expelling their stomach and digesting whatever they are resting upon, such as what the Crown-of-Thorns does to coral polyps.
Mostly nocturnal, these bottom dwelling multi-arm echinoderms are excellent scavengers and some of those mentioned below are extremely easy to maintain, yet some are not recommended for reef systems. A good rule of thumb for reef keepers is to avoid any starfish with knobby backs such as those in the genus Protoreaster. All starfish are very vulnerable to sudden salinity changes, therefore acclimate your selections carefully!