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FAQs about Zoanthid Predators, Pests

FAQs on Zoanthid Disease: Zoanthid Health, Pests, Predator 1, Zoanthid Health, Pests Predators 2, Zoanthid Health, Pests, Predators 3, Zoanthid Hlth., Pests, Pred.s 4, Zoanthid Hlth., Pests, Pred.s 5, Zoanthid Hlth., Pests, Pred.s 6, Zoanthid Hlth., Pests, Pred.s 7,
FAQs on Zoanthid Disease by Category: DiagnosisEnvironmental,
(Pollution/Poisoning, Lighting...), Nutritional, Social (Allelopathy), Trauma, Pathogenic (Infectious, Parasitic, Viral) Treatments 
& Zoanthid Reproduction/Propagation,

Related Articles: Zoanthids, Sea Mat: An Ocean Of Color For The Aquarium by Blane Perun,

Related FAQs: Zoanthids, Zoanthids 2Zoanthids 3Zoanthid ID, Zoanthid Behavior, Zoanthid Compatibility, Zoanthid Selection, Zoanthid System, Zoanthid Lighting, Zoanthid Feeding, Zoanthid Reproduction

Snails of various sorts, Nudibranchs, some mites, crustaceans... Some folks even think Pycnogonids (Sea Spiders) are problematical

Exclusion via quarantine of new specimens is best...
Next, biological controls...
Last: Chemical treatment


   Heliacus snail       Nudibranch       Amphipods  

What could this be?    8/4/16
Hi I found a few of these critters crawling on some Zoanthid frags. You can not see these with the naked eye. I found them with a jewelers loupe and then took these photos with my iPhone under a microscope. Hoping they are a detritivore but I am fearing the worst. Thanks in advance.
<Appear to be Mites/Acarinans... I wouldn't panic. Bob Fenner>


trying to id a hitchhiker on my Zoanthid coral     4/9/16
Hello Crew,
I'm trying to id a hitchhiker that came on my Zoanthid coral. it looks like it has tentacles and is very fast.
<A polyp...?>

it seems to cover my polyps with a tough fibrous film overnight
and also has built a den type cave with a very tough covering, some type of fibrous material and lots of very tiny white sea shells mixed in as well.
<Mmm; a Sedentariate Polychaete.... likely>
it's killing all my Zoanthids
<Unusual; what other life is here? Water quality measures? What changed recently?>

and I haven't been able to see any more of it than 4 small tan looking tentacles that come out and if it sees a shadow it darts back in the rock.
Any input I could get would be greatly appreciated, any questions you have for me I would be happy to answer best I can.
Thank you for your time
<Can you send along a well-resolved, cropped, few hundred Kbyte image? Bob Fenner>
re: trying to id a hitchhiker on my Zoanthid coral
I've been trying to get a pic of what we can see on occasion, but have been unsuccessful so far, if I can get one I'll email it right away
Thank you
<Real good. BobF>

Aeolid Nudibranch ID?      9/14/15
Dear Sirs,
A friend on a reef forum has suggested you may be able to identify these slugs I have been finding in my aquarium. She suggests they might be either *Aeolidiopsis** ransoni* or a *A. harrietae*.
<My money is on the latter. A fave ref. (Bill Rudman)
I'm attaching a
number of photographs of a number of different animals. All have been found on or very close to Zoanthid soft corals within my reef aquarium.
<Do consume Palythoa>

The largest animal is around 10mm long with the small ones being 2-3mm I look forward to hearing from you.
Best wishes,
<Thank you for sending this along. Bob Fenner>

Nudibranch ID    1/11/13
Can you ID the attached pic of a Nudibranch? I believe it is the type that eats Zoanthids, but I see no damage to any of my colonies and I found this guy in the sump. Thanks!
<Mmm, yes... appears to be an Aeolid... do place the string:
"Aeolid predators of Zoanthids"
in your search tool and read re. Bob Fenner>

cropped and enhanced
Re: Nudibranch ID    1/11/13
<Welcome Van. BobF>

Worm ID: Syllid within Palythoa Colony -- 3/9/11
Hey WWM Crew,
<Hey Todd, Lynn here today.>
I found this little critter on my Palythoas and was wondering if you knew what this worm is?
<Yep, it's a type of Syllid, most likely in the genus Myrianida, that's in a reproductive phase. Syllids are generally fairly small worms (couple of cm/<1'), that tend to live either in the upper layers of the sandbed or above it, where they're associated with everything from sponges to corals, tunicates, hydroids, bryozoans, etc. It's a very diverse group of worms.>
I am not sure if it was eating my Palythoas, but it was for sure irritating them.
<I bet so. The last time I ran across one of these guys, it was associated with Palythoas and was indeed either consuming, or at the very least irritating them. I would remove this, and any others that appear within the colony. For more information, please see the FAQ titled 'Saltwater Polychaete ID Question: Syllid Stolonization -- 1/19/09' at the following link (as well as link supplied within): http://www.wetwebmedia.com/PolychaeteIDF7.htm?h= >
My best guess would be that it is in the Class: Polychaeta, but I am not positive.
<Right you are. It's a Polychaete in the family Syllidae.>
Any insight would be greatly appreciated.
<You're very welcome.>
<Take care, Lynn Z>

Hitchhiking Aeolid? Help ID Please... 9/23/11
Ahoy There! Alex again... I'll try to keep this one less verbose than the past few...
<Verbosity never an issue>
As Bob suggested, I added a truly deep DSB to my sump when I rebuilt it and have been having virtually no problems since... My nitrates dropped from 80-100+ to down below 20ppm in about a week (the 50gal water change undoubtedly helped but after resting and testing I was shocked at how much difference the new sump makes) and my phosphates are below 0.5ppm (decreased by a full order of magnitude!), so that's all good.
<Ah yes>
As promised, I will send pictures soon; I just want to let it grow in a little and then I'll write an article for the WWM forum. I learned a lot building my own and I am excited to share.
Anyway, while you're thinking about that, think about this (hehheh): I recently discovered a stowaway in my tank! I know, this is all too common on the high (maintenance) seas, but I can't figure out what this guy is. I can tell it is definitely some kind of Nudibranch, probably an Aeolid but for all I know it could just as easily be from the Glaucidae family, and by my guess it is still a juvenile.
<Does appear to be an Aeolid>
It has somewhere around 4-6 pairs of brownish-orange cerata and a milky-white-to-almost-transparent body, and it looks to be just over 0.25" long (not quite a centimeter). I do not have a submersible camera but after many (literally hundreds) attempts I was able to deftly snap a few halfway-decent shots through a magnifying glass and then zoom in on the computer, which is why these chosen few images are still pretty grainy. I wish I could offer better ones. In these pictures, the big fork that looks like rhinophores is actually (I think) a large pair or cerata, and the two pairs of tiny whitish prongs at the anterior end are what I understand to be the rhinophores and oral tentacles (but these are nearly invisible in all but the top-leftmost image).
I am curious not only because it looks so much like an adolescent *Aeolidiella stephanieae*, but because if it's not then I'm concerned it's probably eating the Zoanthid polyp it's been hanging out on for the past two days (shown in the pictures).
<Likely so>
If it is a Berghia-type Nudi,
<Not likely>
then it's a bit ironic since I was considering trying to find some but I chose peppermint shrimp instead (which, by the way, decimated the Aiptasia in my tank in about 4 days... now if they can just survive long enough to clean up the tiny ones that will inevitably sprout soon after...), but I'd also like to know so that I can make a decision one way or another as to whether I should leave the little guy in the tank or give it to one of my FOWLR friends who actually has some Aiptasia for it to eat.
<Maybe the latter, but I would definitely at least remove from here>
I am dubious that it is actually a Berghia though, because not only does it not seem to have a clear activity cycle (it slowly paces around this particular clump of Zoanthids night and day), but also because I feel like there would probably have been more than one with whatever rock this one came in on. I do not know how small juvenile Hermissenda crassida specimens can be... perhaps I have one that is recently past the veliger stage?
<Doubtful to the extreme in captivity... the water moving pumps, mechanical filtration, lack of foodstuffs of use...>
Zoanthids are in that weird Cnidarian nether-region between a hydroid and a coral,
<Mmm, much more toward the latter/Anthozoans>
so it wouldn't surprise me to learn that H. crassida might be eating them, but I also can't tell with certainty that the polyp is being eaten. These Zoanthids are sensitive enough that I find it equally possible they would just close up because they're being crawled on, and I can't distinguish any areas with visible damage. Unfortunately, I don't know the exact species of these Zoas, so I can't offer much in the way of spotlighting diet preferences to help identify this hitchhiker... I hope this image is small enough to accept. I was trying to retain sufficient
detail in the shots.
As always, your scholarly wisdom is highly valued and graciously accepted.
Oh great gurus, what should I do?
<When in doubt I vac it out; it's a free-for-all! Bob (not Ted) Nugent>

Hitchhiking Aeolid? Help ID Please (amendment) 9/23/11
Sorry to send multiple messages, but I just realized a grievous error in my last note:
I mentioned that possibly my stowaway is a juvenile Hermissenda crassicornis
because I had found a picture of a baby one (possibly misidentified, now that I've looked around more...) that looks very similar to the tiny thing crawling on my Zoanthids. Obviously (to you maybe) that is impossible or at least very unlikely, because H. crassicornis comes from cooler waters than my tropical tank and so is unlikely to have survived long on any rocks from the LFS. But after looking at all the pictures listed under the Family Aeolidiidae on Bill Rudman's Sea Slug Forum species list,
<A fave>
I am still not sure what I've got. The closest match besides Aeolidiella stephanieae might be A. oliviae, with its diet of anemones and maximum size of ~20mm, but the ones pictured are supposedly 12mm long and they have many many times the number of cerata I see on the stowaway, and like the Hermissenda sp. they also seem to be from cooler water.
I will pipette it out of my DT and put it in a jar so I can try to get a better picture.
<Thank you. Plah Bob>

Hitchhiking Aeolid (Better Pix) 9/24/11
Howdy Bob F. Nugent (good to know the 'F' stands for 'Fletch' haha)
<I wish I had the Chevy Chase income, and much more acting ability!>
So taking good pictures of tiny sea slugs with a marginal camera is basically impossible, but after much diligence I was able to get these images. As you can see, the beast has far fewer cerata than *A. oliviae* and actually does have a faint orange stripe down its white back, so perhaps it is closer to being a juvenile *Hermissenda* than I thought (but if that's what it is then supposedly it can get pretty large). I also noticed that the tips of said cerata are indeed whitish-colored, and though none of the blacklighted pictures were worth sending (partly because the camera battery died as I started attempting them), I was able to clearly see green glowing specks within the cerata, which confirms that it *was* eating the Zoanthids (or at least eating their Zooxanthellae). I currently have the creature isolated in a little plastic magnifier box. I still have not seen any others in the tank, so I'm not sure how likely it is this one has reproduced; it is probably a loner. It's too bad I can't keep it; sure is purdy.
<Can/could... either suffer some attrition of your Zoas, risk reproduction... or place/keep/feed elsewhere selectively>
Do these shots lend any better clues as to the species, or even whether I'm dealing with an adult specimen versus a juvenile?
<Not really. Per BillR's excellent SSForum, you'll note that there is often a very large range of colours/markings, variations in size/dimensions per species, geographical distribution>
Note the edge of the straight razor placed for size comparison... If I could confirm that it will survive eating more than just Zoas, then maybe I could put it in my refugium and let it cruise around in there.
<Mmm, most Nudibranchs are quite food-specific... Hence my standard issue of collecting/purchasing ONLY w/ their food organisms>
I doubt it can lay eggs without a partner... Even if it could there's apparently almost no chance that any young would make it through the pumps alive.
<Not likely so>
I still don't know which piece of rock/coral it was stashed on, but at this point it has to have been living in the tank at least a couple of weeks
<Greatly probable>
because I doubt it was hiding on the lawnmower blenny I bought last week.
<Highly dubious indeed>
I have examined all the other areas of Zoanthids in the tank and as yet haven't seen any others, so hopefully I lucked out and only got one. I guess we'll find out...
PS: Kudos for saying 'PLAH' back... most people are pretty dismissive of the idea because they don't try to figure out what it stands for. But I think it's the future of salutation. Now if we can just make it the future of Foreign Policy as well...
<I do agree. Cheers, BobF>

Re: Hitchhiking Aeolid (Better Pix) 9/24/11
Sorry, I neglected to attach the pictures to that last note...
<Mmm, I just cropped and optimized one of the prev.>
they probably still don't help much though... You guys are troopers. Thanks for your help.
<Nos vemos. B>

Treating the tank for Nudibranchs 4/28/10
Hi crew.
<Hi Chris>
I have read tons of stuff related to my problem. I have Zoanthid eating Nudis in my tank.
<Bad news>
My problem is that I can't remove all of them to dip without completely dismantling the tank knowing that the whole process will need to be repeated to eradicate the next generation of Nudis.
<Dipping usually does not work anyway>
I have removed a couple from dipping small rocks and frags and very rarely see them.
<They have to be removed manually. The life-cycle is typically two --three weeks, so daily removal over this period is required. An hours work or more a day typically until they disappear after three weeks. Frustrating. http://www.wetwebmedia.com/corldisart.html >
I was hoping that treating the entire tank with Flat Worm Exit
<A Planarian killer http://www.wetwebmedia.com/fltwmchemcont.htm Nudibranchs are not Planarians. This is a shotgun approach, a 'hopeful punt' that probably won't work>
followed by a healthy water change
<Requires at least two, 50% changes, the same day, the first an hour or so after treatment. This is NOT something I would do, it will kill life in your system>.
and carbon would be a viable solution.
If so, do you have any specific methodology including dosage amount to pass on to me?
<No chemicals that I know of. Quarantine of invertebrates & live rock before adding to the main system to prevent introduction of these in the first place. Hours of manual labour to remove once they are in>.
Thanks for you attention to my problem.
<No problem Chris>

Blue worms eating Zoanthids 11/26/10
First off, thank you for the plethora of information you all make public for the inquiring aquarist. I have spent countless hours increasing my knowledge of my little piece of the ocean and your site is definitely
appreciated. I searched high and low and couldn't find anything on my problem. My Zoanthids are being eaten by what looks like small blue worms.
They look similar to bristle worms but they are skinnier and royal blue in color.
<I see your pic and concur>
They have blue antennae and look to be burrowing along the side of the flesh on my Zoas. Any info on if they're good or bad?
<If they're causing discernible damage to your Zoanthids, I'd say bad. If not, no big deal likely>
As of right now I've caught two (can't see any more right now). If they are pests do you know how I can eradicate them?
<Likely trapping. Read here re:
I hope the attached photo is clear enough it's from my cell phone so it's not the best.
<Welcome. Bob Fenner>

Zoanthid eating snails?
Hi Guys,
I just finished searching many forums and reading through a lot of your site.
Over the last month, I lost various Zoanthid colonies of mine. The colony slowly but surely starts to develop a white film and then just disintegrates (which I know is typical of infection but...). Once I noticed this, I fragged away any healthy polyps as best as I could and those for a while did well, but then also withered away (over a week or so)
I also dipped the colony in CoralRx but that was to no avail as it continued to disintegrate. While I was fragging away some more healthy polyps, I noticed that the colony had hundreds, or even thousands, of these little tiny balls. I am guessing they are some sort of egg as the balls have a mucus like substance that keeps them together when you try to pull them off the coral. In other words, if you pull a tiny cluster of the balls away, quite a few more little clusters follow behind it.
Sure enough, as I started to pull the "eggs" off the colony, under the "eggs" I found various snails. I am not sure what they are, but I am guessing they are the culprit. Hopefully the pictures are good enough.
I would really appreciate it if you could tell me what the heck these things are and if you think they are guilty. And then what I need to do to get rid of them. The CoralRx seems to have done nothing to stop them.
Thanks so much for all the information you provide us reefers. It is greatly appreciated by me and many others.
Take care,
aka - Jgoal55 on RC.
<Do look like predatory snails... Please read here:
and the linked files in the series above, and:
Bob Fenner>

Hungry beast in my tank; makes translucent tubes, burrows holes in live rock, and eats Zoas and candy canes!! 2/19/10
Hello WWM Crew!!
First of all please let me thank you for all you do and for all the help you have provided me in learning how to keep a reef!! You time is appreciated by me!
<We share!>
Secondly, I am sorry to bother you but I cannot find previous posts that show pictures of what I have. Any help you can provide me will be greatly appreciated.
I have not been able to identify the villain(s?) I am battling in my tank.
Here is what I know about said villain:
* builds calcium tubes about 1/8 inch diameter
* makes translucent 'tents'
* dines on Zoas.
* dines on candy canes
<The Nudibranch in your first attached file? Oh yes>
My piece-O-reef is a 20 month old system that is comprised of a 120 display and a 50 gallon fuge. Both display and fuge have a 5" DSB of large grain aragonite with a plenum. Mostly LPS with one piece of healthy SPS.
Around Feb 7th, I noticed enough issues with my Zoas that I decided to take action; my problem is receding Zoas and, many months before that, physical damage (white puffy tubes or tunnels) to a couple of my candy canes. Long ago I moved the candy canes and had not seen the translucent tubes in months. Now they are appearing again near a Zoa frag on the same rock.
<These tubes shouldn't be problematical. Are they illustrated here?>
Two weeks ago I pulled a lone Nudibranch out of my fuge.
<This is a predator...>
Also, upon further investigation of other Zoas in the tank I noticed what I could best identify as Zoa pox (Zoas that would not open and showed white spots around some of them) on about 15% of the Zoas in my display. From looking around it seemed like a fresh water dip in a 7 drop per gallon mix of Lugol's water then a Seachem coral dip was the best course of action.
<Yes, but...>
The problem is that I removed all coral but one for treatment. I left one frag of Zoas in the display (showed no signs of problems); yep you guessed it now that frag is receding and showing the tubes and now a 'tent'. You will notice the 'tent' to the left (lower half) of the frag plug.
<I can't quite make this out>
(also note the hole or 'door' at the bottom of the frag plug)
<Nor this really>
I can remove the last frag but I assume the critter is in the live rock and don't want to give him a chance to hide away to haunt me another day! Do I dip the live rock and kill everything on it? seems a bit like a bull in a china shop approach to controlling the little bugger.
<Which? Sorry for my confusion. Are you referring to the Nudibranch/s?
These are best removed via siphoning... the "tents" and tubes by physical scrubbing (outside the tank)>
On the 14th I noticed an update; 80% of the 'tent' was gone and by Sunday morning the remainder is gone. The Zoas were still in their receded state with no visible signs of external munching or other physical removal just a slow but steady retreat.
<There's something else going on here highly likely... some sort of interaction twixt your other Cnidarian life perhaps. Ideally, after such "processing", the Zoanthids can/will be placed in a system of all new seawater>
Other frags (on the frag rack on the wall) are fairing fine in the tank, three types of Acans, Favia, Galaxea un-named SPS. The Zoas on the frag rack (Mohawks and some other no-named frags) show mixed results. I report them as 'mixed' results because the Mohawk are wonderful but the others seem to be enduring light shock (due to moving the frag rack around the tank while tearing out the corals on the live rock).
I also set up my 'night-vision' camcorder to see if I could catch any critter feasting on Zoas, no luck but boy o boy do I ever have more 'pod' action than I imagined!!
The link to some of the night shot of the affected Zoas:
And finally tonight I hate to say it but at this point the Zoas are almost gone. I tired to take another picture to see if I could get a better shot of the tubes.
To the right of the frag plug just above the middle you can almost make out a translucent tube. The tube extends down between the rock and frag plug.
Also, you can barely make it out but there seems to be "chewed" or "powdered" calcium looking stuff below the lowest edge of the plug. The tubes appear to be able to go into the live rock so I am guessing that the critter can 'burrow'.
<... I have tried to manipulate this image... and still can't see what you are referring to. Sorry>
Please help me identify this beast and point me to the remedy.
Thank You!!!!!!!!!!
< I wish I could offer you more here. I would not add more/Zoanthids to this system. I would vacuum, remove the Nudibranchs, their egg casings. Bob Fenner>

Snails: Likely Collonista Snails, Issues with Disappearing Zoanthids -- 1/6/10
<Hello Tommy, Lynn here today.>
Help, I'm trying to ID this snail.
<Yay, I love snail ID's!>
I'm hoping it's not a Heliacus.
<I think you're in the clear. It looks like a common, harmless, herbivorous hitchhiker in the genus Collonista, sometimes called a 'Mini Turbo' snail. To positively confirm, use a magnifying glass and take a good look at the snail's operculum (the 'trap door' at the opening of the snail). You should see a tiny pit/hole in the center. If you don't see one, do try to get a few detailed photos and we'll try again. Just for comparison, Heliacus spp. (aka 'Sundial') snails tend to be rather squat top to bottom, with straighter sides, a rather heavy, almost 'beaded' appearance to the surface, and an obvious cone-shaped operculum. For more information/photos re: Collonista snails, please see the related FAQ's at the following link: http://www.wetwebmedia.com/snailidf14.htm
More here: http://bb.wetwebmedia.com/viewtopic.php?f=25&t=242
Here's an example of Heliacus spp. snails: http://www.gastropods.com/5/Shell_5765.shtml >
My zoo's are disappearing fast
<Uh-oh. If the water parameters/conditions and other livestock are okay, then I'd look for either some sort of predator or irritator, or evidence of disease. The list of potential predators and irritators is long and includes Heliacus snails, Pycnogonid spiders ('sea spiders'), Gammaridean Amphipods, Vermetid Gastropods, Nudibranchs, a few crabs, various fishes (Angels, Tangs etc.), tube dwelling Polychaetes, etc.(see links below for photos). Your best chance of spotting some of the smaller, and/or more cryptic individuals is at night with a flashlight. If you're able to rule out pests, I'd look into possible disease (pox, fungus, etc.). Take a good look at the colony, especially the stems. Are there any light or whitish spots present? Do the stems look fuzzy, spindly or unusually dark? Once you determine what the problem is, please use our Google search engine for a solution/treatment: http://www.wetwebmedia.com/Googlesearch.htm
In the meantime, we have lots of information regarding Zoanthid problems, starting here: http://www.wetwebmedia.com/zoanthidhlthfaqs.htm
Check out this link for some terrific photos of Zoanthid predators, irritators and pox: http://zoaid.com/index.php? module=Gallery2&g2_itemId=384 >
..and I'm noticing that these snails are multiplying very fast.
<Collonista snails can indeed multiply quickly, but don't usually cause problems.>
These are the best pictures I could get.
<I think we're good to go with this snail. However, as per above, if you find that what you have isn't a Collonista, then do please let me know.>
Thanks for the help!
<You're very welcome!>
<Take care, LynnZ>


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Re: Snails: Likely Collonista Snails, Issues with Disappearing Zoanthids -- 1/7/10
<Hello Tommy, Lynn here again.>
Thanks for all of the help!
<You're welcome!>
I think it must be the asthenia snails
<You mean Asterina stars?>
..doing the damage. I guess I will get a harlequin shrimp to combat these.
<I wouldn't, unless you're absolutely overrun with the little stars. Otherwise, once they exhaust the food supply (of stars), they'll likely starve to death. I would instead opt for physical removal (tweezers work well). Please see the following links for more info re: http://www.wetwebmedia.com/harlshrpfaqs.htm
http://www.wetwebmedia.com/asterinafaqs.htm >
I will have to get rid of my sand star first though.
<It's possible that the star could escape the shrimp under the sand, but I wouldn't chance it.>
I have attached a couple of pictures one is before and then you can see what happened. The other is what the fire and ice look like and it used to be full.
Again Thanks for the help!
<It was a pleasure! Take care, LynnZ>

All around Zoa death ... 11/29/09
Hi all:
Forgive my ramble a bit please!
<Is fine>
I have two NanoCube tanks, both 12g, both using MaxiJet 900 pumps. One of the Nanos is the DX, thus has the 50/50 pair of lights for 48W of light, and the other has a Current USA 18W plus a little 9W, both with 50/50 bulbs for a total of 27W. Water conditions are consistently testing well within normal parameters as far as nitrates, nitrites, ammonia, pH and alkalinity, plus in my efforts to figure out what is going on, I have been doing weekly water changes of 20-50%. All my Zoas were looking pretty good for a reasonable amount of time (2 months or so) and now they are steadily melting or completely dying.
<These and other Cnidarians are hard to keep in small volumes>

Frustrated beyond all belief, I did a Lugol's dip yesterday on the bigger pieces that could withstand dipping (some of my rocks have other critters on them which might not tolerate the dip as well) in the hope that there is some bug at issue here, like flatworms or Zoa spiders. I looked very carefully in the tank while doing the dip under good bright light and with a magnifying glass to see if I could actually spot any "vermin" but in all truth I was only able to see a couple of 'pods and /possibly/ some flatworms at the bottom of the dip tank.
<I've expanded and "sharpened" your image as well/much as I can and see nothing either>
I started the second tank as I felt I was dealing with allelopathy initially, but I fear I may have complicated matters instead of simplifying or isolating the root cause. At his point, all of my Zoa rocks save one are in the process of dying (or so it seems.) There is some other wildlife in the tanks that appear to be doing OK ... pulsing Xenias (plentiful and fruitful), little red "rock anemones" (I don't know what these are really, but I've included some pictures), various mushrooms
<All three groups are tough competitors with Zoanthids>
and some cleaning crew crabs and peppermint shrimp. One of the tanks also has a pipefish who seems to be doing pretty well.
Zoas are really the only thing that I'm seriously interested in having - the other things are somewhat extraneous, so losing the Zoas is quite upsetting and I don't seem to be able to figure out what is going on.
The only things I have not tested are SG and phosphates, although with the frequency of water changes I am doing, I don't think these are an issue (although I could be wrong.)
<Not likely an issue>
My water is sourced from Scripps Aquarium here in Southern California, which is supposed to be NSW equivalent.
<Mmm, was just down there three days back surfing... Not yesterday, the waves were HUGE! And chatting with a young fellow filling containers at the base of the pier, four sand filters... I do hope/trust that you have a S.O.P. for storing, treating this natural water ahead of use. Do read here re: http://wetwebmedia.com/seawater.htm
and the linked files above>
Please forgive the terrible pictures ... I tried my best to show what is going on here:
<I only see one>
In the foreground (fuzzy) are the Zoas that seem to be doing OK ... not great, but OK. In the background is a large rock that used to be completely populated with green, purple and blue Zoas - now, everything is melting dying, and the back half of the piece is completely naked now. I know this is hard to see ... my apologies!
Here is a picture of one of the rocks with the "rock anemones" on it ... these appear to be doing well on this rock. Above this rock is another rock which was moved back into this tank from the second tank; it used to look even more "full" than this, but everything is now retracted or dying:
<Mmm, well... I can't tell/discern what the issue/s might be here leading to the Zoanthid die-off, but I do know how I might proceed... I'd drain one of the 12 gallon systems, carefully (with gloves, eye-protection, outside the system) break off some of the good/clean/live Zoanthids and re-stock the newly cleaned systems sans the other groups of Cnidarians>
Using a turkey baster and blowing off the residue, I find that there are little circular white "rings" that blow off from around the base of the Zoas ... I can't really tell or know if these are eggs or webs or what.
<Likely dead tissue from the Sea Mats>
Does this give anyone any ideas on what I'm either doing wrong or what is going on? This is really driving me to the point of giving up - I'm normally quite patient and willing to try and figure things out, but I've done everything I can possibly think of (albeit from a somewhat newbie perspective.)
<Unfortunately no... only can guess>
Thanks so much! Let me know if there are more specific things that I can address/look for.
<Other than the collective experience we have recorded on WWM re these organisms, I have nothing further to impart here. Bob Fenner>

Worm living inside my Zoa 10/26/09
A while back I took some pictures of this worm looking thing coming in and out of my Zoas, here it is:
This was a while back and eventually I stopped paying attention to this.
But for the past few days the Zoas have been... not extended to their full potential and I picked them up to take a close look.
I saw something that caught my attention. It looked like a shell that was growing between the polyps. I got a tweezers and broke it up, turns out to be a tube. Yeah, it looks like there's tube growing into the Zoas!
<It's just a hitch-hiker tube-dwelling worm of some sort or another (further ID unlikely). It's nothing to worry about and not why your Zoas are not extending.>
You can see it right in the middle
<See above.
Sara M.>

Nudibranch ID help 05/29/09
I can't find a match for this lil critter, the Nudi.s body is apprx. 1/4 "long. Thank you, Paul
<Hmm, can you give us any more information? Did you find this little guy on one of your corals? What corals do you have?
Sara M.>

Re: Nudibranch ID Help: Zoanthid Predator -- 5/30/09
<Hello Paul, Lynn here this afternoon.>
I recently set up a new tank, it was a hitchhiker on one of the frags
<Betcha it arrived on the Zoanthids.>
... it was on the glass, if you zoom in it is actually a beautiful Nudi
<Yes, it is.>
..but I have it in a specimen cup till I can find out if it is safe in the tank.
<Good, because it's definitely not safe around your Zoas.>
It was on the glass not a coral
<Good. What you have looks very much like a notorious Zoanthid eating Nudibranch. They're mostly a brownish/orange and white, but take on the color of the Zoas they're preying upon. For more information, please see the following link, starting at 'Re: Polyp-feeding Nudibranch' all the way down through the 'Re: Perhaps a gorgonian feeder?' posts: http://www.seaslugforum.net/showall.cfm?base=palyfeed
Terrific photo: http://coralpedia.com/index.php?module=Gallery2&g2_itemId=641
More photos, showing color variation: http://coralpedia.com/index.php?module=Gallery2&g2_itemId=415
I'd keep a close eye on your Zoas for any indication of predation or signs of additional Nudi.s. If you see either, please refer to WWM's FAQ's for removal tips. Just enter Zoanthid Nudibranch in the Google search engine: http://www.wetwebmedia.com/Googlesearch.htm >
..but I have frags of Zoas, pipe organ, Montipora danae, chalices and good ole GSP in that tank.
<All but the Zoanthids should be in the clear -- at least as far as these particular Nudi.s go! Take care, LynnZ>

Snails, Zoa Deaths, and good pix. 02/11/09 Howdy! First off my wife and I had the pleasure of meeting Mr. Fenner in Dallas at the Next Wave 2009 event. He gave the most dynamic, and informative presentation. The other presenters had good info, but they were geeks ( in a good way, really :) <Thank you for saying this re Mr. Fenner's presentation. I always try to tell him he's the best, but he thinks I'm just "sucking up" or something. I've been to a lot of marine aquarium conferences/presentations, and many are interesting... but (imo) none are as equally informative and entertaining/well presented as Roberto's.><<Ho buoy! RMF>> Now for my questions. 1: Our Zoas are dying off in patches. We have tried RO and Lugol's dips to make sure we don't have spiders or any other evil critters. Well, we found Sun Dial snails. How the heck do we get rid of them? <You have to quarantine the Zoanthids and meticulously remove all the snails... and, as gently as possible, scrap off all the snail eggs.> We removed 3 or 4, but we keep finding one or two every now and again. We really want to put more Zoas in, but when? <You need to quarantine the infected colonies asap. I wouldn't add anymore Zoanthids until you haven't seen any snails for at least 2 weeks.> 2: We set up a pico tank and found the coolest hitch hikers. We think the coral is a Caulastrea. It is in bad shape, but seems to be getting better! The other is a beautiful snail, any ideas on what it is? Is it evil? <It's difficult to ID snails from photos... but I do think this is one of the Nerite sp. of snails (usually beneficial).> The pix are attached. You can find the originals at http://william1034.smugmug.com/gallery/7329746_Q9Y4q/1/471608269_j6LtS  We are still learning so please leave comments with the pictures. William <Cheers, Sara M.> Btw, you might want to collect those snails and sell/give them to someone with a Zoanthid "problem." I do recall going around with a friends, actually looking for these little guys because their Zoanthids were growing out of control (as tends to happen). Though they're a pest for those just starting out with small Zoanthid colonies (and for those in love with these corals), they're actually appreciated/welcomed by some with more stony coral focused systems (that happen to have some stray Zoanthids run wild). Cheers,
Sara M.

Help! Zoa eating nudis -03/16/08 Hi, I hope you can answer an urgent question- I recently noticed Zoanthids disappearing. Today lost several bam bams. I spotted 2- 1/4 inch long green nudis. Googled them and identified them as Zoanthid predators. It said to use flatworm exit. I have some used it before and a different tank. I need to know if this will hurt my RBTA. <The problem with these types of broad scale "medications" is that you never really know what they're going to affect in a reef tank. It might hurt other animals in your tank indirectly. It will kill any flatworms you have (benign or otherwise) and this could also hurt other animals in your tank (some flatworms are toxic upon death).> The package material says it is safe for reef inverts but I would feel better if I got an expert opinion first. <Expert opinion? Hehe... will you settle for mine?> Need answer quick, those buggers are munching away at my Zoas as I type. <My advice would be to remove the Zoanthids to a quarantine tank, and try your best to remove all the Nudibranchs by hand (with teasers under a magnifying glass) and also find and scrape off all the eggs (cheap dental tools you can get at a pharmacy work well). The problem with using flatworm exit for Nudibranchs is that you usually have to use a dose on the order of 5 to even 10x the recommended dose. And who knows how safe or not safe such a treatment is for a whole tank? I wouldn't risk it. If meticulous removal of the pest doesn't work, I would try the flatworm exit, but only in isolation (if possible).> Thank you so much in advance Linda Mecher : ( <Good luck! Sara M.> <<RMF would try the "usual assortment" of probable small predatory wrasses here as well.>>

Bristle worms and Zoanthids -01/29/2008 Hi Guys, I did a quick search on WWM but couldn't find anything quickly. I just added a very small frag of Zoanthids (after a 10 min dip in Lugol's soln.) into my main tank. This afternoon I got home from a long night shift and found at least 4 sm. bristle worms crawling around them. I pulled off 4 not sure they were good or bad for the Zoanthid and I am completely exhausted from my night shift. Could you just tell me if bristle worms attack or have a symbiotic relationship with my new little frag? <Neither really, they typically just coexist in peace.> I really appreciate it. Thanks, going to bed now. Erika Villanueva <Sleep well, Sara M.>

copods and polyps... comp.?  12/1/2007 Hi all, <Zac> So I have an abundance of copods <... there is no such thing> in my 24gal tank, I have seen a slow decline in my daisy polyps, meaning that they have been slowly disappearing from my once large and healthy colony to a very small colony. My water quality is <20ppm nitrates, 0 nitrites, 0 ammonia, 8.1 ph. I do 5gal/25% water change every two weeks, so I don't think that it is my water quality. Anyway, I keep seeing tons of copods in my tank, seeing that they have no predators, because I only have 1 sandsifter goby in my tank right now. I see the copods all over the daisy polyps at night, and also on some red zoos that I have, which are also starting to diminish. On the other hand I also see some tiny blue star fish that are on the daisies and the red zoos, so that might also be the problem. But I have no clue. Thanks, you guys are great. Zac <... What else is in this system stock-wise? What re your supplementing, feeding practices? Could be that these small crustaceans, copepods or otherwise are predaceous... BobF>

Zoanthid eating Nudibranchs   11/30/07 I recently found quite a few Zoanthid eating Nudibranchs in one of my tanks, we have a few that are plumbed together. We have pulled off as many as we can find, dipped them in an iodine solution and pulled off all the egg spirals we can find. <Good> The colonies that are infested are in QT now. My question is this: when the eggs that we haven't found hatch do they have a free swimming larval stage, and if so would a UV sterilizer prevent them from making their way into my other tanks. <No> Is there anything I can do other than quarantining them and pulling the Nudibranchs off with tweezers? Do you know of any fish that would eat them that I could add to my tanks? Thanks for all your help. Amanda <"Eggs develop and hatch as free-swimming veliger larvae with a rudimentary coiled shell. The shell is lost with the larvae metamorphosing into a miniature adult settling on the bottom." (WWM) More rapid, complete physical filtration might sieve them out. Bob Fenner>

Blue Zoa BUGS!!!  8/20/07 Hey crew, Thanks in advance for all the info already given and provided to us all. Your site/info has been a great resource for me and am sure for others. I am wondering if you could ID these bugs I recently found on my blue Zoas. These bugs seem to make the polyps close randomly in groups. Getting a great picture if these bugs has been tough without sucking or attempting to suck them out with a baster. Less than a millimeter in length, clear, has 2 antennae coming from its head, has multiple legs cant tell home many because its so small. The Zoas and the rock are teaming with these bugs. I have attached a picture to help, don't know how much help it might be. I can always suck one out with a baster in order to get a better picture if needed. Thanks for all the help for giving me a good understanding of what is needed in order to take care of and maintain a marine Aquarium. <Mmm... well... there are a few approaches to control here... with the usual "range of desirability"... biological, physical, chemical last... You can/could interpolate these by a cursory read here: http://www.wetwebmedia.com/swmitefaqs.htm Do you have another "isolation" tank that you might use to eradicate the bulk of these pests? Bob Fenner.

Re: Blue Zoa BUGS!!!  8/20/07 After reading am not to concerned about these bugs just the number of them and the Zoas not opening or only opening for a shirt time. Well, I have am still working on the tanks filters, its an all glass not drilled tank and invested in an overflow with Aqualifter pump, I had plans to have a isolation tank plumbed inline back to sump for an isolation tank. At the moment it is not set up. I do have a 10gal tank sitting around. Thank you. <I do think you're wise to ignore these for now. Bob Fenner>

Re: Blue Zoa BUGS!!!   8/24/07 Thank you for all the help you have been, I think for now I will tolerate the spiders, but if continues to be a "major" problem which already seems to have lessoned I will be adding a wrasse. Thanks again Bob for all the help. -Jay
<Welcome my friend. BobF>

Re: Blue Zoa BUGS!!!   8/22/07 I could have told you that Bob! Joking aside I should have mentioned I did move them to a quarantine tank anyways, despite the lack of concern. Thanks to you all wise one, really thank you. Am i better off to leave them in quarantine till they are gone or population diminishes? Also since moving to quarantine I have been able to monitor the Zoas more closely. There are a few white worms with black spots maybe reverse black with white spots curled up on the sides of a couple closed Zoas, probably more on the underside of opened Zoas. also 3 maybe 4 long red stringy worms, almost looks like a piece of red hair flopping about over the sand, coming from under the rock which the Zoas are growing on. My question now is what would be better for the Zoas. From my understanding 2 ways would either be Interceptor or freshwater dip in RO water, adjusted ph and temp of coarse. With addition to these new findings of critters which is better to elevate the problem, interceptor or freshwater RO dip? <Mmm, FW... pH-adjusted... but... I see in your next email that these may be "something else"... Pycnogonids... do they have eight apparent legs to your eyes as well? If anything, I'd go with a purposeful predator here (Lined Wrasse sp. likely)... or just tolerate them if they were mine...> Sounds like ro dip would be better but I am worried of specimen loss, and I am wandering if the Zoas will be able to handle the additional stress levels from a freshwater dip. Thank you wise one, Bob, for making me reconsider my previous statements/actions/concern. <Mmmm, BobF>

Re: Blue Zoa BUGS!!!   8/22/07 Once I put it in Quarantine I was able to get better photos, I have attached 2 pics, to show the infestation and 1 showing the actual "bug" itself which turns out looks more like a grasshopper, a very small grasshopper. <... or a Sea Spider... Please read here: http://www.wetwebmedia.com/pycnogonids.htm and the Related FAQs file linked above. Bob Fenner>

Re: Blue Zoa BUGS!!!  8/23/07 Thanks for the quick reply once again. Figured you were tired of hearing from me, the unwise. Well I see eight legs very hard to determine but definitely looks like there are 8 legs. I noticed when I first put the Zoas in my main tank my Pseudochromis fridmani (spelling?) was picking at the rock, not to sure it was eating anything or not. If I were to get a 6line or a line wrasse I'll run into compatibility issues correct? <Mmm... in a tank this size, I give you good odds of not having real trouble here> 75gal 110lbs live rock. I fear with me having the Pseudochromis fridmani (was my first fish), already has his territory staked out pretty much all the rock on the bottom half) that he will go after a lined wrasse if introduced into my system. I notice with some research to use caution when putting these 2 species together, as long as they don't resemble each other, or need to be introduced at the same time? <The Lined Wrasses are pretty sharp, and fast!> Combination of both? Or just plain luck or am just stupid for even trying to put these species together in the same tank. I would just as easily return the Pseudochromis fridmani (AND THE TWO 3 STRIPED DAMSELS!!!!) but I can not. Girlfriend picked them out for our first fish so kinda stuck with them till he dies (hmm.... gives me an idea, j/k). Thank you Bob you have been of great help. -Jay
<Welcome Jay. BobF>

Zoas hlth.   4/24/07 A few days after buying some Zoas the colony died off.  Now I have white spots on my remaining colonies, which appears to be tissue damage.   It reminds me of chicken pox.  They don't show in photos, too small, but appear to be growing. They don't move. Please help identify and suggest a treatment. <What type and wattage of lighting are you using? Strong halide lighting can induce a condition that sounds similar to this?!> What is the best method for dipping Zoas? I currently use an iodine dip. <No special requirements, just drip acclimation> Ken <Olly>
Re: Zoas hlth.   4/24/07
After investigating further, it appears to be some type of small snail. <Possibly young Heliacus? See here - http://www.reefs.org/hhfaq/snails/photoalbum_photo_view?b_start=1> Ken <Olly>

Zoanthid spiders, Pycnogonids, MgCl2 dipping...  4/18/07 Hi,      I know you have talked about these before, but I couldn't find the answer to my question on the previous forum.      I am a newbie and did not know that I should QT corals (I know better now).  Somehow, somewhere, I have picked up Zoanthid spiders.   <Pycnogonids... some of which do feed on Zoanthids... some are "just" space commensals...>      So far, I have FW dipped the affected zoos, dipped them with coral dip   <... what is this? Oh, the Kent Product... mainly I2 cpd.s> and QT'ed them.  They have been in QT for about a month.  I didn't see anything for the last month, but recently began to notice that some of the zoos looked puny and were drooping.  Tonight about 2 hours after lights out, I turned on the lights and saw a baby spider.  I immediately FW dipped the zoo and got another.  I dipped all the zoos in the QT and got a couple more.  I have had about enough.  This is so disappointing.  I finally just tossed the affected zoos tonight. <?!>      I am writing because I am worried about the zoos that dipped clean on the first go round.  I left these guys in my DT and they seem to be doing fine.   I plan on doing another FW/coral dip tonight on the ones that are not attached to rocks and see what happens.        If I find more spiders, what should I do? <Remove, and dip (in a 1.024 or so spg MgCl2 (Magnesium Chloride) solution (made with clean freshwater...) for half a minute... place all in a new, non-infested system...> I have several colonies that are attached to base rocks in my tank.  If I find spiders in some of the colonies should I take out the base rock and dip/QT it too? <You could... but starving these Pycnogonids out will do the same... just leave them, the existing system w/o food for a month or more...>   I probably weighs about 20#.      I hope you all can help me decide what to do.  I love this hobby but am getting very close to bailing because of the disappointments.  I also received some flatworm infested Chaeto from my trusted LFS.  Now my refugium has a few of them.  What should I do?   <Read... on WWM re...>      Will a sixline wrasse help at all?  Will they eat these things?      Thanks,      Miri    <Read on my friend, read on. Bob Fenner>

Re: Zoa and Amphipod Problems... Unrelated   3/21/07 Hello <Hi!  Mich here.> I read through a bunch of text regarding predatory amphipods..  There seems to be some conflicting info about whether they are carnivorous or not..  I'm having problems with some Zoanthid colonies ceasing to open during the day...  Some of the colonies were originally 50-60 polyps and reproducing extremely fast..  About a week ago they stopped opening..  The first day they didn't open I did a 10min freshwater dip to check for nudi.s...  Nothing showed up at all.. I placed the colony back in the tank and waited until the evening still nothing..   About 2am I check on them again.  My main lights are off at this time so It's a little hard to see..  There are about 40 of these "amphipods" (I'm not really sure what they are) swarming all over the colony that stopped opening plus 2 other colonies..  I watched them for a couple of minutes and it definitely looks like they are pulling off pieces of the Zoas..   <Mmm, pulling off algae.> My tank parameters are as follows..  Bare bottom 33g, 60lbs of rock, EuroReef 5-2, 150w heater, Seio 620, 150w MH de pendant..  The sump is filled with Chaetomorpha.. kH 10-12 calcium 450 <Allow to drift under 400> magnesium 1300 Ph 8.0 ammonia 0 nitrite 0 nitrate > 5 temp 77-78f I was hoping to find out for sure if these things are eating my Zoas..   <No.> I'm also looking for suggestions for control of these critters..   <Not recommended.> Maybe some sort of Wrasse..  Any and all info would be much appreciated.. I'm providing  a link to a picture of them..  I'm not sure how to attach it to this email..  I originally tried to take a pic of them in the dark with flash and they all scattered.  The pic came out all blurry so this is the best I could do..  A couple of them came back after a few minutes so I snapped this picture.. http://i30.photobucket.com/albums/c306/fishnfst/evilpods99.jpg <A very nice photo.  These are scuds (Gammaridean amphipods) and are not the source of your problems.  These are harmless, beneficial creatures.  I suspect you may be seeing them scrap algae of your Zoanthids.  I am not sure of the cause of your problems, but I have found that increasing the circulation to these closed up Zoanthids can help.  You might try adding a power head and checking your outlets, perhaps your circulation has been unknowingly reduced.  I hope that helps.  -Mich>
Re: Zoa and Amphipod Problems... Unrelated   3/21/07 Thank you very much for the prompt reply Mich.. <You are most welcome!> I did remove one powerhead from my tank recently..  I thought I had too much flow with two Seio 620's and a Koralias 2..    The tank is only 24"x20"x16"tall.. Flow seems adequate still with only one Seio 620 and my mag3 return pump...  I will add one power head back to see if it helps.. <Hopefully it will!> Off Topic:  I appreciate the easy going and concise answers.  I was originally apprehensive about sending my question due to fear of getting my grammar and spelling ripped apart in an open forum :)   <No need to fear! Underdog is here... Oh wait, that's something else!  There really is nothing to be apprehensive about.  If there is an effort made to follow the posted directions you won't have a problem.  But you would be surprised by the blatant disregard for requests of proper grammar and spelling we receive.  We get queries filled with "i this" and "i that" or ALL CAPS or just chat room speak "cuz it ez".  We do not want to post anything in this format.  We use these queries to educate and help others.  It must live up to a certain standard to achieve this goal.  We are all volunteers and it is time consuming to fix all these problems.  After a while it can get exceedingly frustrating, especially for Bob, who has dedicated thousands upon thousands of hours of his life building this site.  We provide a free service and ask for very little but an attempt to keep things on a level where all can understand and benefit.> Thank you for going easy on me..   <No worries my friend.> If you can post the pic to my reply it would be much appreciated as well.. <Oh, but of course!>.   Thanks Again,
<You're welcome again, -Mich>

Snail ID: Possibly Sundial snail (Heliacus sp.)   3/3/07 Good Afternoon, <Good Morning I guess!  Mich here.> While having coffee this morning I observed a moving speck, which turns out to be a snail. <What good eye you must have!> At present my aquarium houses two Astraea and three Turbos. Also there have been no recent additions in the last three months to account for recent hitchhiking. The shell on which the snail is perched is app. 1"x1 1/2" to give some idea of scale. Thanks in advance for any information, <Hmm, Is a bit small, but does look an awful lot like a Heliacus snail, which are predatory on Zoanthids and typically nocturnal.  Do you have any Zoanthids in your system that are experiencing any difficulty?  See this page, next to the penny:   http://www.wetwebmedia.com/polypdisfaqs.htm  Heliacus snails have a small pagoda shaped operculum (trap door) this may help with identification.  Hopefully is not a Sundial snail (Heliacus sp.)!  -Mich> Jane
Re: snail id: Possibly Sundial snail (Heliacus sp.)   3/4/07 Mich and crew, <Hi Jane! Mich with you again.> Thank you for the link to the image--the wee bugger in my tank bears a striking resemblance to the Heliacus. <Not good.> Unfortunately, due to its small size and my lack of x-ray vision, the operculum was/is too small to see.   <Magnifying glass?> Difficulty with Zoanthids is now past tense--little left but a rock and red stubs. <Uh oh!> But, thanks to you, I can see the light--now if I can only see the snail(s) again... <Hee!> Regards to all,
<And to you and yours.  -Mich>


Little crawly critter I.D. 1/28/07 Hello Bob or Graham, <GrahamT again, Steph. Did you miss me?> This is Steph. I had a few "green bubbles" on my button polyp, which, after looking on your site resembled bubble algae. Removed those, only a few. <Hope you read on the preferred method for "bubble algae" removal, using a siphon, etc.> Now, I see some whitish, long, and slender "bugs". Some of them are on the sides of the tank and some crawling on my button polyps....are these a good thing? <Hmm, still would like to see these, rather than go on a verbal description. I am inclined to believe that you are ok, though. -GrahamT.> Steph 

Hair algae, P. diadema, and Zoanthid rejuv. 1/25/06 Hello folks, <Deb, glad you could join us.> Thanks so much for all of the helpful information. <We *try* to be helpful!> In the next 6 months, I'm going to be upgrading this tank to between a 150g and 250g system.  At that point, I will make my 55g into the sump for the main tank.  I will either section part of this off for a refugium, or I've got a 20g that I can hook into the system as a refugium.  When I do this, my canister filter will go away, and I will be implementing a DSB in the main tank.  Until I can do this, I plan to continue weekly 20% changes (replacing one section canister filter media each time), continue aggressive skimming with the CPR BakPak, and continue to ensure that the current in the tank is strong. <Very glad to hear that you are moving beyond canister-filtration. You will be moving into a much more versatile/useful configuration.> At this point, my Cyano problem has seemed to cure itself.  In doing the weekly water changes, I found that the pump servicing my SQWD system was clogged.  This was inhibiting water flow significantly in the tank.  Now that I serviced it, there's a pretty strong current in the tank, which probably helped to eradicate the Cyano growing in the tank.   <Most likely, this helped a lot!> Also -- my Halimeda is making a comeback, though I still need to continue cleaning hair algae off of it every couple of days.  The bubble algae is still present in the tank, but somewhat manageable, as I can gently pull it out during water changes and dispose of it. <Are you sure you have bubble-algae? Sometimes, I think folks think BGA is bubble when it has gaseous packets in it's layers...> So, the only real problem in the tank is the hair algae.  It's still growing quite rapidly.  In trying to fix this problem, my bicolor blenny stopped eating and has "disappeared" in the tank.   <Maybe he needed a vacation. Heck, if I had to eat hair algae...> I'd like to pickup a lawnmower blenny to replace him and to help with the hair algae problem. <Remember, Deb: This is dealing with the symptoms of a water-quality issue. IIRC, your last phosphate test was .03ppm, and I was asking how sure you were of the accuracy of that result. Where do you stand now? Did you ever buy a new kit?> Once the hair algae is gone, I plan to supplement his feeding with various algae foods (as I already do for my Coral Beauty). <Should pose little problem with a little research...> Adding him will result in having the following fish in the tank:  1 coral beauty, 1 Dottyback (Pseudochromis diadema), 1 yellow-tail blue damsel and 1 lawnmower blenny.  Does this seem like a sound decision to add this fish? <As long as you aren't hoping for a total massacre on the hair algae, yes. In my experience, algae-eaters always choose to ignore the one thing you bought them to eradicate.> Otherwise, my Zoanthids have stabilized a bit.  They're not dying off anymore, but they're not flourishing as they've been for the past few years.  Only a handful are opening up, and not fully at that.   <All this points to a water chem. issue to me.> I'm hoping that they are on the road to recovery.  I'm supplementing the daily feedings now with Cyclop-Eeze, in hopes that the added nutrients will encourage their growth.  I also use a plastic turkey baster to blow water over them with each water change to try to free them of the hair algae that grows around them. I've ordered new test kits for my phosphates, silicates and nitrates, and they should be arriving any day now.   <Ahh, very good. A reputable, reliable manufacturer, I hope. Mmm, one note: Silicates aren't a factor unless you have huge diatom blooms, so worrying about the concentrations is moot IMO. I don't own a silica test kit.> I've taken the water changes down to 1x per week, 20% using RO/DI water.  I've just gotten new cartridges in for the RO/DI unit and will be replacing them this week. I've also cut back my lighting schedule, taking 1.5 hours off the back end for both the daylight and actinic lighting. <Good steps, all.> In doing all of this work, I've realized that I haven't replenished my cleanup crew in years.  I've still got about 10-15 Astrea and turbo snails in the tank, but all of the small crustaceans are gone.  I'd like to replenish this crew, but am afraid that any crustaceans I add will be decimated by my Pseudochromis diadema.  Any ideas on what types of inverts I can get to replenish this crew that will survive the presence of the Pseudochromis diadema?  Having a well stocked cleanup crew may also help with the algae problems in the tank. <Hmm... I never worried about a P. diadema bothering hermits to the point of murder. Types and compatibility of hermits is not a strong-suit of mine, but I know we have the info here on WWM if you look for it.> So, to summarize: -Lawnmower blenny for this tank -- good or bad idea? <Good, in your case.> -Any ideas on how I can nurse my Zoanthids back to health? <Provide optimum water conditions: temp, movement, quality, feeding, lighting spectrum/duration.> -Any ideas on how I can supplement my cleanup crew without buying an expensive smorgasbord for my Pseudochromis diadema? <Mmm... *I* don't see a problem with the "generic" red-legged hermits here. (RMF strike me down if I am in error)> Thank you so much for all of your help.   <Oh, Deb. You know we love you. -GrahamT> Deb

Hydroids infesting my Zoanthids? Dear Crew, <Russell> Here's a new one for me...maybe you also? <Could be> Over the holidays my Zoas (four frags, about six months old and previously healthy) closed up and became infested with little critters. My Ca and dKH dipped mildly when I was out of town for three days, but otherwise the tank was stable.. (need to get a calcium reactor, my 2-part dosing pump is temperamental). These parasite-like things attach to the closed polyps and are too small to photograph accurately. They look like a small (1-3mm) hydroid-ish creatures, having a clear stalk with small white-brown tentacles. They start like white little dots and grow pretty fast, spreading to all colonies and show tiny tentacles. I had hydroids on my tank walls last year, but they went away after a month or so. <Typical> Last week I removed the frags (some had already grown on to surrounding rocks) and did a 15 minute dip in a gallon of tank water with a salinity of 1.015 and over a tablespoon of Lugol's... at the same time blasting the frags with a turkey baster. This seemed to do the trick upon reintroduction... most polyps re-opening and looking good. <Good> Then, over the last two days, the little critters came back so last night I re-dipped the frags- same as above except for 30 minutes AND I followed this with a flash RO/DI water dip. I also pruned and discarded the remaining small amount of new growth- polyps left behind on my LR (figuring these small stragglers were still infected and causing the problem). <Mmm... much more likely to be residual animals in your system... really need to dip, move the Zoanthids to another setting> This morning the frags, for the most part, are open with no obvious critters. Could these be hydroids?? <Oh yes> I've searched this site (and others) and am confident it is not "reef pox" which is more pustular, ulcerative in nature. If these apparent parasites come back, any other ideas???? <Mmm, plenty> Interestingly, I also recently picked three Nudibranchs off the Zoa frags. I don't think the infestation is from Nudi eggs. Also, they are not Zoa spiders. Thanks, Russell in KY <Hopefully gone for good this time. Bob Fenner>

Zoanthid Eating Nudibranch...Not Hydroids After all! - 01/25/07 Dear Crew, <<Hello Russell>> A couple of weeks ago I wrote to you that my four small Zoanthid rocks in my 11 month old tank were infested with hydroids.  You offered good advice. Upon further observation, and research, these are actually small Nudibranchs. <<Uh-oh...not the "better" option>> They are about 2-6 mm in size, light brown, and very, very annoying. <<Indeed>> I dipped the four colonies in fairly concentrated Lugol's with a SG of 1.014.  Then I did a flash FW dip.  I don't have a pH meter, so I just added a small amount of tank water to the FW; hoping to buffer as well as I could. <<Not likely much of a factor here>> It seemed to work.  All zoo colonies opened up and did well. <<Hardy little buggers those Zoanthids>> But now- really, based on my research, not much of a surprise- two have the little creeper's back on them. <<Yep, a few adults/egg strings were probably still in the display while you were nuking the rocks>> My next step is to remove all four rocks and place in my QT, with periodic dips. <<A good move, though I would only perform the dips if/when the Nudibranchs are sighted>> The nudi's only seem to be going after my zoo's, and not my softies or LPS. <<They are likely "obligate" feeders on the Zoanthids>> No SPS in my tank yet... and certainly not until I take care of these Nudi's.  I have heard Nudi eggs are hard to kill (I am a family physician and have the same problem getting lice eggs out of my patients' hair)? <<Usually more "resistant" to attempts to eradicate, yes...but I think your plan to remove the Zoanthids from the display will allow any remaining eggs to hatch and die out...not unlike leaving a tank fallow when treating an Ich infestation>> Besides Lugol's (which, I swear, has to be the same Iodine I use to clean wounds in my office), <<Ahh, but it is mate!  Lugol's Solution (named after the French physician J.G.A. Lugol's...and also called IKI (Iodine Potassium-Iodide); Iodine, Strong solution (Systemic); and Aqueous Iodine Solution BP) is a mixture of 5% iodine (I2) and 10% potassium iodide (KI) in distilled water with a total iodine content of 130 mg/mL>> any medicated dips you can suggest? <<I think the Lugol's is fine>> I suspect the only thing I can do is QT, do freq dips and, essentially, use tweezers to pick them off for the next, say, three to five years... <<Ha!  At least you have a plan [grin]>> It's ironic that hobbyists have the hardest time keeping the large, pretty Nudibranchs alive and, at the same time, can't seem kill off these prolific little buggers.... the Aiptasia of slugs. <<All comes down to providing an adequate supply of the appropriate foodstuffs my friend>> Thanks, Russell in KY <<Always a pleasure to assist.  EricR in South Carolina>>     

Zoa Spiders    11/27/06 Hi, <Hey Shelton, JustinN with you today> I have an outbreak of Zoa Spiders in my 99% Zoanthid tank (70gal) I have used the "dip" on all new comers, although up till now I have never used a QT for corals :( <Better late than never, I always say :)> I have setup a QT & removed all my Zoas from the main tank, fresh water (pH adjusted & temp)/Lugol's dip on them, & found approx 40ish spiders in all! I have searched all over the Net & posted on forums both this side & is the US, but no-one really seems to know much about these spiders? <Mmm, a Google search for the term "Zoanthid spiders" turns up many results on many forums> Sooooo I'm hoping you might help in the reproduction (do they lay eggs on/in the polyps or do they keep the young with them until big enough to fend for themselves? <Yes, they do lay eggs in the polyps themselves, but I don't think there's any tending by the paternals. I believe they hatch, and eat the Zoanthid from the inside out.> Secondly I've been checking the Zoas after lights out for more spiders, so far have not found any, but I'm thinking of dipping them all again after say 10-14 days to make sure? <I would do an additional one at 5-7 days of QT just to be safe> Finally (sorry) <no worries> how long do you think it would be wise to leave the main tank free of Zoas so if there are any left in there they starve to death? I was thinking 4-6 weeks possibly? <I can't seem to find any information on this, incidental or otherwise. Likely, after the 2 week quarantine, you will be fine, but if you have the facilities to wait out a full 4-6 week fallow period, it wouldn't hurt.> Many Thanks, Shelton (UK) <Glad to be of help, Shelton. Good luck on getting those nasty suckers out! -JustinN>

Strange Zoa Infestation  11/21/06 Dear Bob (or whichever if the wonderful crew answers this) <Hi Claire, JustinN here with you today>   I have a problem with the Zoas in one of my Nano tanks.  All the polyps have closed up, and they seem to have white dots in them.  When we squeezed a polyp, a tiny white pin head sized thing came out, which appeared to be slug like.  I have also caught 2 Polyp munching Nudibranch  - could this be the young of the Nudibranch, infesting the polyps?  I don't think this is what some people refer to as Zoa Pox, but I could be wrong. <I would be inclined to think it to be more likely related to the Nudibranch, however a quick Google search turned up some pictures linked to the term 'Zoa pox' which look suspiciously like what you describe.>   What should I do to treat this - iodine dip - freshwater dip - would flatworm exit work? <An iodine dip would be my recommendation here. 1 tp 2 drops of Lugol's iodine solution per gallon of pH adjusted RO water should do fine. While Flatworm eXit does seem to have quite a following on many message boards, what you describe does not sound to me like flatworms, nor can I condone its use in an active reef environment.>   It has spread so fast that it is alarming.   I would really appreciate any help.   Kind regards, Claire <I would try the pH-adjusted iodine dip before moving into panic, and if you have the facilities, quarantine this specimen until you have a better identification of what you're up against. -JustinN>

Turbo snails harming my polyps? 7/5/05 Hi Crew, <Hi - Ted here>           I wondered if you could help me? I have a 30 Gallon tank, fully cycled, has been running for about 10 weeks now. Vitals are as follows; SG - 1.022, Temp - 77, Ammonia - 0, Nitrite - 0, Nitrate - 15ppm, pH - 8.1 Lighting is only 2 x 30 watt fluorescent tubes (1 x daylight plus - 1 x Actinic blue moon) Inhabitants are; 1 x red legged hermit (about 3/4 inch in size) 2 x unidentified "hitch hiker" crabs ( 1 tiny one and one about an inch) 2 x Turbo snails Some Chaetomorpha. I have some Yellow Parazoanthus polyps on a small piece of live rock positioned a few inches beneath the surface because I know my lighting leaves a lot to be desired. I am concerned for the polyps' health though. I sometimes notice a turbo snail on the rock, it doesn't appear to be eating them but it does look as though it could be harming them through pure clumsiness (knocking them and pressing against them with its shell) The same goes for the hermit crab too. Their health does seem to have declined since I started adding other livestock (they were the first live inhabitants). Some of them never open now and one of the smaller ones has actually vanished, some of them sometimes look as though they have been squeezed at the base as they go thinner (almost as though they have had fishing line tied around the base and tightened). I feed them weekly with a small amount of Mysis shrimp (soaked in SeaChem reef plus) squirted on to them with a syringe which they appear to eat in earnest. There is also an abundance of pods and bristle worms in the tank. Do you know what may be causing the decline of these polyps? I really like them and would love to keep them. (they have been in the tank about one month) Sorry for the long message but I wanted to cover as much as possible in one mail. Best regards and thank you for whatever you can tell me. <Your water quality seems fine although I'd like to see the nitrates lower. The presence of pods and worms are an indication of good water quality. While polyps will retract when disturbed, they should extend again so the snails are not likely the problem unless they are constantly disturbing the polyps. Your lighting may be contributing to the polyps decline. Keeping the polyps near the light is a good thing but adding more light would be better. You might also check the water flow in the tank. Chaotic water flow will help the polyps. Finally, true crabs are opportunistic predators. I would caution against keeping them in the tank as they may view your other inhabitants as food.>            Leif, Birmingham, UK. <Good luck with your tank - Ted>

Zoanthid Predators? Hi Crew,  <Hello Brandon> I've got a pair of fire shrimp, L. debelius, and have them in my refugium. The day I received them, I also received a new book specifically on inverts. In this book by a leading author, it mentions that fire shrimp have been known to regularly feed on soft corals and Zoanthids. I have several small colonies of very rare color morphs of Zoanthids, and this comment has given me much concern. Have you guys seen this behavior, or heard the same things?  <No, I've never heard of them eating zoos and I see no warnings on LFS sites about this. James (Salty Dog)> 

Green " Sponge" growing on my Zoanthid Hi, <Hello there> I have some type of green sponge or algae growing taller and taller on my Zoanthid, should it be removed? <Maybe... can you cut a bit off... take a close look to see what/which it is?> If so, how would I remove it without killing my Zoanthid? <Best by working at the conditions that favor this material over your mat polyp: Please read here re Algae Control: http://www.wetwebmedia.com/marine/maintenance/index.htm > I have read the following paragraph but I'm not too sure how to removed it and how to know if this is the type that should be removed. Thanks for any help.  Annie-Martine from Toronto Canada Symbioses: Many Zoanthids live in close association, either commensal or mutualistic with other species, particularly sponges and algae; and they "get along" with most other kinds of sessile marine life as well; neither quickly overgrowing them or being supplanted by true corals, other Zoanthids, Corallimorpharians or even some anemones. Regardless of their innocuous nature, Zoanthids should be purchased without their symbionts. Die offs from specimens purchased with sponges and algae are way too common. To repeat; the exception to the rule of Zoanthid hardiness is the ones that come attached to commensal sponges and algae. Many of these perish easily. <Do take care if you're going to try cutting the pest material away... the Zoanthid itself is quite toxic to humans... wear gloves, and wash these thoroughly afterwards. Bob Fenner>

Aiptasia on Zoa Stolon Hello Gang, I have a question I was unable to find in the archives. Do you have any safe methods for removing Aiptasia from a Zoanthid colony stolon? The Peppermints haven't touched them, and I don't have enough to support an Aiptasia eating Nudi, and squirting Kalk has caused too much collateral damage. I'm stumped! Thanks for your help. Brook <Hello, Brook MikeB here.  Your situation is difficult to say the least.  I would suggest trying a different product that Kalkwasser.  Have you tried Chem Marin's "Stop Aiptasia" or "Joe's Juice".  They are usually successful at eliminating those buggers.  Let me know.  MikeB.>

Nudibranch assistance Thanks for great website. <Thank you Chris for the compliment, MacL here with you tonight> I found few opisthobranchs on my reef they were around my expensive blue zoos and pink zoos I removed 3 of them yesterday night but is there any better way than wait for them to show up and catch them? <Youch that's a big problem. Honestly I have heard there are traps but I've never seen any that truly work other than just pulling them off.  Also I have friends who isolate their zoos to try to catch them.  Usually they show up more at night so with a flashlight and/or with a red-light?> One of them were on my orange zoos and it's some tassels color was orange I am sure it is eating my zoos (Some reason starting 3 weeks ago all of my zoos are not doing good (all other corals are ok) I could not figure out why but now I know...) <They can be terrible problems. let me also recommend you look on www.seaslugforum.com> Since my camera is not so good it looks like this http://www.wetwebmedia.com/nudifaqs.htm Nudibranch id 6/11/03 Thanks Chris Kim

Strange Encrusting/Smothering sponge 7/25/04 The sponge in the attached photo has slowly been covering this zoo frag, and seems to be smothering it.  I have asked on a forum but no one had seen anything like it.  Any identification info or what I should do about it would be appreciated. thanks, Rusty <no pic or attachment came through my friend... but we can still chat about it. Sponges are commonly associated with Zoanthids. Some are harmless or beneficial, some are parasitic and others are indeed simply another reef invert in competition for space. I'd suggest that you do remove (screwdriver or sharp chisel will be fine) some of the polyps from the sponge (use latex gloves to protect yourself from palytoxin). Clean the polyps off with a toothbrush (no worries) and pat the Zoanthids dry before super gluing them to a rock (see more info in my "Book of Coral Propagation" and elsewhere on the Internet). We also describe and illustrate some of these species in our "Reef Invertebrates" book. Anthony Calfo>

Vanishing Polyps Hey guys <Scott F. is the guy tonight> Thanks for all your help over the years. I have another question. My yellow polyps seem to be disappearing. The ones that are there look ok, but their numbers are decreasing.  I also have several other corals including xenia (my h20 quality indicator) all growing quite well.  All tests are where they should be: ph 8.3, sal 1.0025, ca 420, alk 10dkh etc...  I have 2 theories.  1st- they are low in the tank. Maybe not enough light?  I have 5w/gal VHO in a shallow 50g breeder w/DSB, so they're about 10" deep, but slightly shaded from another rock outcrop. <These colonial anemones are usually quite durable, and adapt to a variety of lighting schemes and environmental parameters. Your lighting seems fine> 2nd- The other night, I saw a couple of these bugs about 8-10mm looked like a cross between a camel cricket and a roly-poly. Brown in color. Occasionally I'll see an exoskeleton floating around the tank.  Anyway, they looked like they were eating at the base of the polyps. Maybe they were eating something around it, I'm not sure, but something's causing these things to disappear one by one while the ones remaining look ok. Ideas? If its the bugs, what can I do to keep the population in check? Thanks for the help. Neil <Well, Neil, I doubt it was the "bugs". These are actually amphipods, most likely, and are highly desirable creatures to have in your system for a variety of reasons, not the least of which is that many species of fish (wrasses, dragonets, etc) love to eat 'em! Aquarists often go to great lengths to "cultivate" "pods" in their systems, so consider yourself "blessed"! It's hard to say from here what is causing the polyp population to dwindle. Your environmental parameters and lighting sound acceptable. I am assuming that no other corals are in contact with the polyps? Do you have any fish in this system, or perhaps crabs or shrimp of some type? I had an arrow crab once that absolutely snacked on my yellow polyp population-ate 'em one by one! Now, that is probably not a typical occurrence, but it goes to show that you need to look at things beyond the obvious. Do review your livestock and see if there are any "suspects" among them, such as angelfish, butterflies, or other fishes that are known to eat coral polyps. In the absence of poor environmental conditions or obvious disease, I'd operate on the assumption that there may be a predator in the mix somewhere-but not the "pods"! Good luck! Scott F.>  

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