Who’s eating my zoas?

Discussion in 'Coral' started by JVU, Oct 8, 2017.

  1. JVU

    JVU Supporting Member

    With my recent new tank upgrade I wanted to start growing zoas. From the recent frag swap as well as purchase from Diablo with the gift card I won at the swap, I got frags of 2-5 polyps each of: rasta, eagle eye, bam bam, utter chaos, blue tubs. I placed them a few inches apart on a rock at mid height along one side of the tank, with the idea of growing a garden.

    They were doing well for the past few weeks with new buds starting, when 4 days ago suddenly 2 of the 5 completely disappeared overnight. No tissue left, no apparent culprit hanging around, just a cleared surface. 2 nights later the rest of them vanished completely. I never saw anything munching on them or even interested in them. So my assumption is it is something relatively large chomping them down in a couple bites and then moving on.

    I haven’t kept zoas in a few years, but I had lots of larger palys in my previous tank without any problems. All of my fish/inverts/snails are from my prior tank and haven’t had similar issues with them before. I’d like to get your best guesses on who ate my zoas because I’m determined to try again and am willing to move or sell the offender if needed.

    My primary suspect is my cowrie, who I’ve had for years without issue, but not previously kept with zoas. I’ll list out everyone here:

    Fish: Yellow tang, blue tang, coral beauty angel (another candidate but I’ve never seen nipping at any coral for years), royal gramma, ocellaris clown, mandarin.

    Snails: Arabian cowrie (medium size, prime suspect), fighting conch, variety of other standard small CUC (trochus, astrea, nassarius, cerith.

    Mobile inverts: Cleaner shrimp, coral banded shrimp, royal urchin, orange linckia star, large serpent star, lots of mini serpent stars, several small blue-leg hermit crabs.

    I have read that when they don’t have enough food to graze on several of the omnivores including the cowrie can go after soft coral. I was aware of that and while the tank/rock matures I have been intentionally over-feeding lots of varied foods and have 2 clips of seaweed out all the time, including near the sand bed. I’ve seen the cowrie as well as the rest of the cleanup crew munching on it happily.

    I’m so upset but I don’t want to make any rash decisions and I’d like your opinions before I act. Thanks for any help.

  2. I'm tempted to set up a live cam and stream it on youtube and bait it with some zoas
  3. Gablami

    Gablami Supporting Member

    Never had an Arabian cowrie, but a quick google search and your list of livestock, seems like the cowrie is it. Would be more surprised if it was the coral beauty.

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  4. L/B Block

    L/B Block Supporting Member

    Aren't angels in general, coral eaters. Or least Whenever I look one up. Person at LFS told me NOT to get a coral beauty because they do eat corals.

    Webcam is a good idea. Get a cheap polyp and see who the offender is!
    Sorry to hear though-

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  5. JVU

    JVU Supporting Member

    Thanks for the advice. I’ve been wanting to set up a cam anyway, maybe this is my excuse.

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  6. daddio

    daddio Supporting Member

    You can use an old ios device and download the Presence app. - FREE.
  7. Flagg37

    Flagg37 Colorado member

    I have a cowrie too. I haven’t caught him munching on any but I’ve had several small polyp zoas go missing overnight. The larger ones seem to be safe. In my case they were no name cheap ones so I wasn’t too disappointed. Yours seemed to be extra hungry. I’ve read that as they get older/larger they increase in their risk.
  8. JVU

    JVU Supporting Member

    Flagg- Yeah I read that too... and mine is about 3 inches long which I think is on the larger side, I’ve had him for years.

    Mark- I’ll check out Presence. I did try another of those turn-your-iphone-into-a-webcam apps last year for my tank, and after a lot of fiddling with it, it would work sometimes but then lose connection a few hours later sporadically, and had no easy storage option for recall. So I gave up on it. I can try again with Presence, or just get a real camera, they are getting cheaper/better. Any other fish-tank specific suggestions in this regard?
  9. JVU

    JVU Supporting Member

    Anyone else have thoughts on which critters could be the culprit?

    And if it’s the cowrie, do you think he would do well in my refugium with chaetomorpha or would I need to re-home him?

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  10. xcaret

    xcaret Supporting Member

    Oh man... you need to stalk the culprit; the last thing you want to be hunting for is an eunicid? worm.
  11. rygh

    rygh Supporting Member

    Are you SURE those are really blue leg hermits. They may not be.
    I have had a Coral Beauty for many years. Never a problem, but there are many stories out there of them getting an appetite for coral.
    I would suspect that fish, or some other inhabitant that you do not know about.

    You can also put coral + suspect in the fuge/sump, and see what changes.
  12. xcaret

    xcaret Supporting Member

  13. JVU

    JVU Supporting Member

    Hopefully I don’t have some nightmare predatory worm, I have all new rockwork and brought over my coral and livestock individually.

    I don’t know how to be completely sure I have blue-leg crabs. They were purchased as such and look like them to me and have remained small. I’ve never seen them mess with any coral.

    I did move my cowrie into the refugium today and I bought some more zoas and new LPS from Diablo today, placed into my display.

    I’ll try to set up a Presence or some other web cam app for my phone and use it to monitor but I suspect I will need a real camera if I want to be able to see what is happening in the dark.

    The scientist in me agrees that I should place zoas in with the suspect cowrie to document that he is the problem by seeing him obliterate them, but the pet owner in me is having problems with that approach.
  14. Chromis

    Chromis Supporting Member

    You said zoas never went MIA before getting a lot of zoas from one shop at once. My first guess is you brought home a zoa eating nudibranch with the new corals, or the superglue under the zoas gave out (were they freshly glued to bright white plugs?)
    Ranjib Dey likes this.
  15. JVU

    JVU Supporting Member

    Those are good thoughts. To clarify, I actually got the 5 different zoa frags from 5 different people (frag swap plus Diablo Corals), though I did add everything essentially at once.

    The reasons I didn’t think it was superglue giving out is that they were doing great for a few weeks then one night I lost 2 complete sets of zoas and 2 nights later I lost 3 complete sets. Plus I searched carefully for dislodged polyps and didn’t find any. My new tank build is empty enough that I would have seen something.
  16. Gablami

    Gablami Supporting Member

    Lol. You'll eventually have some extra zoas that you won't feel bad experimenting on. I'm already working on mowing back the ever encroaching zoa line.

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  17. xcaret

    xcaret Supporting Member

    Just keep a watchful eye, some predators grow from a tiny size where they don't eat that much to a size that seems a lawnmower just passed.
  18. JVU

    JVU Supporting Member

    So twice now I have found my small red/orange starfish eating something on a new zoa rock. When I pulled him off, I don’t think there were any zoas missing but it got me thinking about him more critically. I decided he is actually probably a red thorny starfish, which some people say is reef safe and some say isn’t when older. He is still small but I’ve had him for a few years so I guess he’s older. What do you guys think?


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  19. ashburn2k

    ashburn2k Webmaster

    You want that starfish to eat all your precious softies?

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  20. Chromis

    Chromis Supporting Member

    Has he grown since zoas started disappearing? That's a good sized starfish is all I'm saying

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