Could you elaborate on the sand sifters and the fauna?Yeah, the double star is likely going to be just as difficult as the Linckias (as biofilm eaters, they have a similar diet), and sand sifters are known for depleting the fauna in the sand bed then starving. Honestly, at this point the only tropical true starfish that seem to do really well in our tanks are Aquilonastra species (known in the hobby as Asterina starfish, though Asterina is actually a different genus in the same family as Aquilonastra, and Asterina stars are typically predatory). Beyond that, the next best thing we have are the non-green brittle/serpent stars.