I've got them in my 120 gallon sps dominant system it's also hooked up to a 100gallon grow out tub and I rarely ever see them show up in that one. When they do appear they go to the main display and if the shrimp don't have a meal in progress I've watched them run down the side of the tank after the ones I've dropped in. It's funny to watch especially with the bigger starfish, they will start jumping off the glass while I'm temp acclimating the bag that the starfish is in.Those shrimp must have a crazy appetite! If I can keep enough Asterinas in my other tank maybe I can have a stable enough food source to get harlequin.