I have lots of starfish: 2 orange serpents, 1 reddish/ purple serpent, 1 brown banded serpent, 1 "caribbean" serpent, 1 green and white harlequin serpent, 1 green brittle star, 1 blue linkia, 1 red small fromia, and a sand-sifter, as well as countless asterinas and hundreds or more tiny brittle hitchhikers. But the best of all have been 2 black and yellow brittles I got from Steve at Horizon. They never hide, and remain high on my rocks and out in the open, cleaning their respective territories better than any others. He gets them in fairly frequently, but I haven't seen quite the same ones elsewhere - except in the Shimek "Invertebrates" book, where there is a very nice example. I certainly agree with the other posters regarding mechanical cleaning and flow, etc, but I gotta recommend these guys - They've been working away for 15 - 20 months.