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I have an interesting view on the matter although likely only to me lol
My tank is one gallon, all of them have been, and I've been purposely stocking asterinas for 8 years in them because the little echinoderms fit the scaling of the aquascape perfectly and if I keep about 15 of them in my pico reefs you can nearly always see one or two on the glass which just makes the reef look so great to me. If I could find something that ate zoanthus sociatus I would buy that too, the zoanthids are my new aiptasias that are overgrowing my reef. I -wish- asterinas ate zo's...any genera of them, but they don't. Since I don't have fish, anything that looks and acts reefish helps my tank to look like a larger one.
The lFS used to just pick some out of the sumps for me, until about the 4th year of purchase they got smart (supply demand) and started charging me 3 bucks because the $20,000 dollars in pico reef supplies and stocking I've paid them since 2001 isn't nearly enough from a niche hobbyist lol
The inner workings of the reef is too complex to tie these coral issues to asterinas, my pics show zoanthid success in spite of huge numbers of them actually on the zoanthids. I am 99% sure they crawl over zoanthids to eat the slime, detritus and bacterial floc associated with grouped octocorals. I have never ever ever seen them actually eat a zoanthd. I have seen them cup over the top of a zoanthid for 24 hours, move off, and the zo open just fine same coloration. Now the zo's are overtaking my dendrophyllias, if blue asterinas (which I've also never seen in ten years) will do the job I will pay someone to ship me a handfull. it can't be asterinas...especially when Ive overstocked them in systems 1.10th the size of the tanks you guys use where my current vase, the one in the pic, is nearing five years and probably has 25 asterinas and 15 micro stars Im just guessing...Im only posting this picture to show I need help with zoanthids, not that Im losing them lol.
I have not found any coral they damage yet and I've been looking since the early 2000's. I know there are strong anecdotal reports that they do eat corals. Let me chalk that up as the 25th thing that doesn't happen in pico reefs that seems to always happen in large tanks
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