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How do Asterina Starfish reproduce? (those tiny starfish on your glass)


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Does anyone know how asterina starfish reproduce? Ive got a huge one thats been roaming around my LR and he looks like hes about to burst (>1 inch).


I like these guys and I just wanna know when Im going to get more.

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I think the population I have is legit. They seem to prefer the non-coralline parts of my LR and I havent seen any direct coralline loss from them yet.

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When you start to notice white spots on your otherwise clean coralline, you may have a problem. Otherwise enjoy!


Actually... Now that you say that Ive been having some bleaching problems with my coralline but since this is a new tank I assumed it was due to light acclimation or something... the coralline is only bleaching on the very top where it gets the most light while the shaded areas are still thriving.


Think it's the asterina or light (im using crappy weak halogens that came with my tank) or something else?


left pic is bleached, right pic is in the shade thriving



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Have you ever noticed how no three stars of that genus in your tank have the same number of legs when found side by side on a surface thats constant fission but man it sure is slow. I've had a seven legger for about 3 years now, still the same.


over the years I took several pics of before and after zoanthid+asterinas and can truly say not once have I seen them eat anything in a reef tank other than detritus. they got a bad rap as zoanthivores never saw that manifest.


I too get some coralline spotting white at times and although stars are not my chief suspect in place of ion command, it wouldn't be surprising if they were able to exploit that reef substrate for food thats an interesting thought to say they eat coralline. will start watching for that in the future


my LFS used to give em to me for free when they were seen as zoanthid eaters

now they charge me three bucks o~

the number one reason I buy them and keep about 20 in my vase reef is because they fit the scaling for the bowl. all reefs need to feature a starfish or 20, and these are perfect slow movers that complete the scape, scoop up some detritus and are really tough over several years in a given reef

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I have had asterinas that have munched on my GSP.


Seems very variable among individuals.

Generally i let them be, but if i catch one on my corals i throw it out, never had any really big problems with them.

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Asterina is a genus with many different species which have different diets. I have seen them eat zoas and coralline algae. Others are detritivores. Just watch and see what they hang out on, they are probably eating it.

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imo its just surface grazing. have never seen them move from a given area to another a leave a line of bare...for example. I would indeed pay money to buy zoanthid eating ones to place directly on my zoanthids. they are so matted and knotted up under and over my dendros there is no saving them now.


that one in the pic is extruding his gut in feeding response they are not normally that open nice macro.

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  • 2 years later...

I spotted one on the back wall of my tank day before yesterday. First one I've seen in my tank. I sat and watched this morning as it pulled itself apart and turned into two starfish. It was one starfish with six legs. Now it's two starfish with three legs. Fascinating! Will keep my eye on them and make sure they don't disturb anything valuable in my tank. If I have a population explosion I'll get a harlequin shrimp.

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I have been pulling them out bc they have been eating all of my coraline its still very purple but im slowly seeing more and more and my coraline is slowly disappearing

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In smaller tanks it's usually hard to miss 'em before the population booms, and to keep them in check with a few judicious sessions of pruning. They really don't reproduce THAT fast (ask anyone who's added a harlequin shrimp just to deal with asterinas and then found they've swapped the starfish problem for a food procurement issue). The horror stories usually happen in larger tanks where there's enough rockwork for a sizable population to build up without many being visible at any one time. Then they exhaust the available food supply of algae and go predatory on some variety of coral.


I've got 8-10 speckled brown ones left in my 9 gallon that have proven themselves out to be coralline/film algae eaters. Coralline algae spreads quickly enough that I'm glad to have the help keeping it in check...I hate scraping the glass and enough's on the rocks to re-seed in short order.

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