Tropical Fish Forums

[carbon-mantis]

Well, as long as I've had marine tanks, I've had Asterina starfish inhabiting them without any problem. Sooo, the other day I received some small (1cm) tree coral frags and placed them in my tank, and within an hour, I notice that where the coral was placed there was one of those starfish. After prying it off, I see that it has eaten the coral down to a stub. Starfish was introduced to the flush, and that was the end of him. I found this incident rather odd, as I have xenia and zoanthids and they've never touched them. I really don't want to get rid of them just yet, as they're nice little scavengers, nibbling on everything from detritus and waste to bits of coralline algae. What are your thoughts/experiences with these creatures?
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ego cogito ergo sum

[FloridaBoy]

Some of them do eat corals, some don't.
Keep in mind, many starfish have very specific nutritional requirements that are never met in aquaria, even though they may actively feed on algae and prepared foods. Ergo, they are always actively eating, yet still slowly starving over a long period of time.

Since most echinoderms exist in our aquaria in various levels of slow starvation, I think it's possible that only after reaching a certain level of starvation (for specific nutrients) they are triggered to attack the living corals, but that is merely a theory. Let's also factor in the reality that only certain select species of corals may be suitable for their food, which can also lead to confusion.

Shimek has reported that the coral-eating forms MIGHT be a different species, constituting less than five percent of the various populations:
http://reefkeeping.com/issues/2004-12/rs/index.php

That's the funny thing about our experiences, they will differ.
Depending on the author, some claim to have no predation problems at all with them thriving in peace, others have branded them as coral munchers, and now that your experience backs this up, you will need to use discretion when adding new corals. It is my understanding that Harlequin shrimp will eat at least some of these nocturnal echinoderms. More opinions here:
http://www.nano-reef.com/invertebrates/?id=9
http://www.garf.org/Star/starfish.html
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Keepin' marines happy for 25 years

[MarkLehr]

Agreed. I have not had any problems in my reefs, but these have been softies and LPS corals. Personally, I tend to roll the die and take chances with a lot of my livestock. It depends on your risk tolerance, so to speak.