I think I’ve got some starfish!

Sleepydoc · Jul 21, 2018

I was feeding my fish last night and noticed something on the side wall of my tank that looks an awful lot like a starfish. Then I noticed another one on the back wall. Except I’ve never (knowingly) purchased any. They must have come as hitchhikers either on some live rock that I purchased, but that was almost a year ago, so it’s odd that I haven’t seen them before now.

They’re about 8-10 mm across. When I checked this morning, the one on the side wall had moved about 6” and the one on the back wall was gone, so they’re definitely mobile. Is there anything I should be concerned about with them? They obviously weren’t a planned purchase, but it’s kind of cool to have them.

Dree · Jul 21, 2018

They’re Asterina Starfish. They don’t get any bigger than about 1cm accross. They don’t prey on coral or inverts or have really any harm in the tank. They do just randomly appear and disappear.
There have been cases of which people have noted them eating their zoas. I personally haven’t experienced this, and I’ve got about 40 zoa colonies, and have had these starfish by the hundreds at once.
No need to worry about them unless you actually see one causing a problem.