Starfish with more than 5 arms...

[Lil' Horned Blenny]

I was wondering whether all starfish with more than 5 arms are unsuitable for a reef tank or are there some good many armed creatures out there. I found an eight armed blue and red one in my tank about 2inch, which I transferred to my husbands FO tank as I didn't think he looked to trustworthy

[Jadinop]

The number of arms has nothing to do with a starfish being "reefsafe". Red Fromia stars typically have 5 or 6 arms and they are a nice addition to a reef tank. Sounds like you have been given some quirky advice.

[tdwyatt]

Small Asterina spp. are sometimes called "Comets" due to their comet-like appearance of 4 or 5 short arms and one long arm (arms = rays), this occurs due to their ability to reproduce via fission (fissiparous asexual reproduction) that results in one or two long arms going with one part of the body, then growing two, three or more new arms to replace those lost with the other part of the fission. Many sea star reproduce in this manner, or may regrow lost rays, resulting from trauma or predation.

As already mentioned, it is not necessarily an indication of anything else in either their behavior or a predictor of a predatory or corallivorous nature.


HTH