I do have 2 starfish in my 29Gal Bio Cube. 1 is a red brittle star doing quite well but you never really see her out. Every now and then you see a tenticle sticking out from somewhere. And I have another star fish all I know it to be called is a red sea star. I have a post on here, an older one that has a pic of it. Its is doing very well does not get picked on and loves the back of my tank most likley due to the algea that grows there. She is always there, and in plain view. I actually got her when the tank was quite new, and almost 2 months later she is still doin her thing.