Yes to feeding the shrimp starfish, but it seems like we made the mistake of thinking the asterinas in the tank were enough to sustain it. I think we may have let it starve completely not meaning to. We also placed a chocolate chip starfish leg in the tank and it didn't look like the shrimp ate the tube feet on it after a week or so. If we didn't starve it to death, some research I found said that trigger fish may kill harlequins. We do have a gorgeous blue trigger that killed a Goby awhile back, and I wonder if that's what happened to the harlequin.