i set up a tank with some live rocks and some corals but i just notice some thing that looks like a 6 legged star fish... i looks and i think its called Asterina. just wondering if it will harm my corals
Asterinas generally aren't a problem with corals. I have read that there are some that are predatory on coral but the one's that are more common aren't a problem. Keep a watch just to make sure, though.
Dont sweat them - if they start popping up everywhere you can give em to someone that has a harlequin shrimp - theyll eat them. I wouldnt get a harlequin though for your tank unless you dont mind buying starfish for 25 bucks at a pop to keep it alive. They will devour a load of asterinas and if no other stars that they eat in the tank will starve