Hydroid Myrionema 01/20/09
Hi Crew,
<Aloha Clay>
I have a problem with what I believe are hydroids (myrionema) and would like to get your advice. The photos that I have seen online appear to match what is in my 90 gallon reef tank. There are 4 or 5 small patches on a large rock that is a little larger than a football. The rock is located on top of 2 equally large rocks forming a cave so it would be easy to pull. I have not observed the hydroids on any other rock. From research on your site and others, the options for controlling or killing these are not great. Since the rock is easily removed, should I just pull the rock from the tank to prevent further spread?
<This is one option. But it's an extreme one. If it were me, I would take the rock out and use a Dremel saw (or a screw driver and a hammer) to chisel off the parts of the rock with the hydroids. Then rinse the rock off very well with salt water (preferably from your tank-- you could even do a water change at the same time). You can't just scrub them off or else they'll grow back. And if you don't rinse the rock really well, some fragments of the hydroids might remain and grow back.>
I have 2 nice leathers attached to it that I can frag and salvage. However, there is very nice GSP colony that I fear will be lost since one of the hydroid colonies has begun to overgrow it. If I remove the rock, what damage will this do to my biological filtration? The rock represents probably 15-20 percent of my total rock. The tank is 1.5 years old and I haven't added anything for 6 months so I am not sure how they got into the tank. Can these creatures lie dormant in the rock for long periods? Any advice you can provide would be greatly appreciated.
<Do try the method described above-- might spare your rock and your corals.
;-)>
Thanks,
Clay
<De nada,
Sara M.>

Digitate Hydroids. Danger? Control?  11/29/08
Hello WWM Crew.
I recently added some Live Rock into my tank and noticed that i have a few Digitate Hydroids. I have searched the internet to find out about them and i have read that these give a nasty sting to corals.
<That's not always true. It depends on the type of coral and the type of hydroids. Some hydroids are harmless.>
Several other websites have advised to get rid of these as soon as possible, several different methods have been mentioned, including Kalkwasser Paste, Injecting with Vinegar. The problem i have is that the piece of Live Rock they are on is full of
Polyps and i do not want to kill these.
<Are you sure the hydroids are stinging your coral? You should be able to see signs of this on the corals. It will look as if they've been "burned" or they will be closed up around the hydroids. If you don't notice any obvious signs that the hydroids are stinging the coral, I wouldn't risk doing more harm than good by trying to kill them.>
Some other sites have said that these creatures thrive on high nitrates and phosphates and therefore when my tank has gone through the cycle that these will just die, is this true?
<This is a possibility. In any case, theses kinds of animals usually come in waves and will likely die off on their own eventually.>
I can't seem to find much information on these, if they are so bad, surely there would be more information out there?.
<I wouldn't worry about them unless you can see that they're doing damage.>
Thank you for taking the time to read this, and any help or advice will be appreciated.
Kind Regards
Jo
<De nada,
Sara M.>

Re: Digitate Hydroids attn Sara 12/02/08
Thank you kindly for your response. 12/01/08
The only reason i noticed the hydroids is because the polyps were all shriveled and grey and never opened,
<Oh, that's no good.>
which makes me think that these hydroids have killed them. I don't really know what to do next, I have been told that the hydroids can multiply and take over. I am not sure about adding any corals now, as I do not want to kill them.
<Unfortunately, if the hydroids are growing right up against your corals, I don't know what you could do to kill them that wouldn't also hurt the coral. What kind of polyps are the coral? If they are soft corals, you could try removing the coral from the rock...>
Any advice would be appreciated
<Reducing nutrients and pollutants in your system is always a good thing...
so if there are ways you can do this, it can't hurt.>
Thanks Jo
<Best,
Sara M.>

Hydroids: growing problem..., control  11/29/08
Hi there!
I am about to give up my fight against brown hydroids. Read some nice article on how to kill them with calcium hydroxide paste (Kalk) but it doesn't work. Tried brushing and even crushing a layer of LR surface (a few millimeters at least) with coral cutters. Nothing works.
<One "last" thing you can try is NaOH mixed with Kalk. See here:
http://www.asira.org/killingaiptasiaxeniaetc >
They seem to borrow in the rock and retract several millimeters within the LR. I read that Berghia Nudibranch are useless against them. I also just read that limpets, and possibly keyhole limpets in particular, could eat them. Is it really worth a try?
<I don't see why not. I'd try to get as many as possible of them with the NaOH... then maybe see if the limpets can help keep them from coming back.>
What specific limpet species should I use to try eradicate the brown hydroids?
<I honestly don't know... but these critters will vary from individual to individual (not merely from species to species). I would suggest you ask Morgan Lidster at Inland aquatics. If anyone would know, he would.
http://www.inlandaquatics.com/>
Otherwise the only other option I see is changing all my LR, but that is quite an expense and a lot of trouble and in the end there could be a few left somewhere under a coral (even as a medusa...).
<Oh no... don't do that! Try these other things first. If all else fails, I suggest giving up. Seriously, in my experience, sometimes giving up sometimes works eventually. ;-)>
Thanks for your advice!
Dominique
<Best,
Sara M.>

Re: Hydroids: growing problem... 11/29/08
Thanks a lot for the NaOH tip. Will try it soon (will talk to the pharmacist -who knows- otherwise will order from Fisher sc.).
<Oh, no need to speak to a pharmacist... just look for "Red Devil" drain cleaner... it is, more or less, pure NaOH. I get mine on eBay.
http://shop.ebay.com/_W0QQ_nkwZredQ20devilQ20lye
Just... again, as the site says, be VERY careful with it. It DOES burn.>
Very interesting site too Asira.com, didn't know it.
<Thanks... is my own personal creation. ;-)>
And for the limpets I already sent an e-mail to Morgan Lidster.
<Ah, good... he is one of the "best kept secrets" in our hobby... likely more knowledgeable than any of us here, save Mr. Fenner. But unfortunately, he is a bit of a recluse. If you ever go to a MACNA, I highly suggest you seek him out... just be sure to carry a good bottle scotch with you (his weakness apparently).><<Heeeee! You DO know Morg! RMF>>
Thanks again!
Dominique
<De nada,
Sara M.>  

Re: Hydroids: growing problem... 12/03/08
Hi!
Does Sodium hydroxide precipitate Phosphate (like Calcium hydroxide [Kalk] does)?
<Good question... I imagine that it does to some extent and for some phosphate. But I certainly wouldn't use it for that.>
Thanks!
Dominique
<Best,
Sara M.>

Hydroid, ID, control...   11/14/08 Hello all! <Mariusz> I was hoping you could give me an ID (ie. scientific/common name) on this Hydroid. It was taken from: http://www.wetwebmedia.com/hyzoanidfaq.htm (i have also attached the same pic). I have a bunch of these in 120 tank with about 140lbs of live rock. <Mmmm... can't tell the species from this small pic> I recently took all fish out of the tank to let run fallow after a parasitic infest. Most corals have been removed (for other reasons). All that is left are a few mushrooms and leathers, peppermint shrimp, hermits. The tank has been running fallow for 6 weeks now and I'm in no rush to put my livestock back in. Also for 6 weeks I haven't put any food in the tank either, it's just been running with Deltec skimmer (which hasn't produced much as I have almost no livestock and no feeding). So questions: 1) are these hydroids a danger to fish? not sure how potent the sting is. <Could be... if they're unaware, get too much exposure> 2) How can I rid these with out manual removal as I've been trying for almost a year. Not sure if these guys are worms of some sort and if de-wormer will work, possibly Prazi or other. Is there any biological alternative? Without proper ID its been difficult moving forward towards a solution. Thanks <Can be very difficult... frustrating up to the point, extreme, of making it reasonable to bleach/kill all LR, start over with some new LR material placed over, amongst, using the killed rock as base... Otherwise, you might be lucky to discover a predator (perhaps an Opistobranch...), but even here, they wouldn't eliminate all... "So many chickens, so many foxes"... Bob Fenner, who would bleach, nuke>

Re: Specific tank questions... Hydroid contr.  – 07/14/08 What would a LFS do with the rock with hydroids? Just wondering. Matthew Harless <Mmm, a few approaches to control... nutrient limitation, predation, poisons... Read here: http://wetwebmedia.com/hyzoancompfaq.htm BobF> Re: Specific tank questions I'm sorry I meant why would they want to take them from me? You suggested that I sell/trade the hydroid infested rock to a dealer and I was just curious why they would want it. Not an important question, I was just curious. Matthew Harless <Mmm, that profit motive thing... "One persons noisome Mushrooms is another persons income"...the future belongs to commerce. B> Re: Specific tank questions I misunderstood. I thought you meant to sell them the brown hydroids (myrionema), but you were talking about the Corallimorphs. Thanks for the clarification. Matthew Harless <Ahh! Thank you. B>

Hydroids, control  – 6/4/08
Hello again Crew,
<Hello>
After a hair algae explosion, I now have an explosion of hydroids (see pic below).
<No picture attached…>
They are covering all of the surfaces inside the aquarium and sump. I don't mind them because they are simply demonstrating the "fertility" of my aquarium.
<Rather the polluted state. Plague levels of a single organism are never signs of a healthy ecosystem; biodiversity is the key.>
They're very small, so should I be worried about them stinging?
<Yes. Many hydroids pack a wallop.>
Will my snails and/or hermit crabs eat them and/or the hair algae?
<No. Careful control of nutrient, overfeeding, etc. will thin the herd.>
Well, I have to catch the bus.
Thanks in Advance,
<Welcome>
Random Aquarist
<Specific Benjamin>
 

Hydroid jellyfish -01/29/2008
Hi,
I have a lot of these in my tank glass. I try to use the magnet cleaner to scrape these off, but their number never seems to reduce. Is there a way to remove these from the tank? Thanks in advance.
<Patience and time work best. These things typically have population boom and bust cycles. You can help things along by scraping them off with a razor blade (if a glass tank), and suck them up with a water change.>
Regards,
Kash
<Best,
Sara M.>
 

Stinging Hydroids HELP w/ pred. control   - 4/7/07
Once again I'm back for expert advice..
<Okay>
I've done some extensive reading on stinging hydroids on your site.
In fact, I've found my pests picture here http://www.wetwebmedia.com/hyzoanidfaq.htm
Article: Bad boyz- hydroids 12/30/03
You've mentioned in other articles that these have few reef safe predators.
<Yes... though these are often quite "species specific">
What would the predators be of the "tube like coiled at the base" string hydroids ?  
Nudibranch is one critter that keeps coming up.
<Some species... definitely not many/all>
I have sooo many at this point, scraping them off would take forever.
Thanks,
Chris
<Well... the path may be long here... and not one I would take... experimenting blindly... If you want to go this predator route, FIRST (dang, that's bright), you should determine as closely as practical, which species of Hydroid you have... will require the use of reference works, a microscope likely... I'd try writing some folks on the Net who work in the field of taxonomy, biology of the Hydrozoans for suggestions here... Bob Fenner>

Re: Starfish and Hydroids?  Blue Linckia (Linckia laevigata) Better Left in the Sea.  2/9/07
<Hello again Travis!>
Thanks for the great info, Mich!  I'll avoid the blue Linckia star!
<Very good!>
Follow-up question:
<Sure.>
Would any/all starfish be damaged/irritated by crawling over rocks covered in hydroids?
<Yes, it is possible.>
i.e. If my rocks are mostly covered in hydroids, do I have to rid my tank of them before I could add any (non-sand-dwelling) starfish?
<Mmm, no, but again not for the reasons you state.  I am hesitant to recommend any starfish that are of the "rock scrubbing" type which I believe you are considering.  Most just don't do well.  Serpent and brittle stars should be fine.  I wouldn't recommend the sand sifting star either, as it will take out much of the beneficial fauna in the sand bed and then starve.  Hope that helps!  -Mich>   
Travis.

Hydroid control? 1/27/07
Hello...this is Stephanie.
<Hi, Stephanie! GrahamT here.>
I am new to nano reefing.
<Welcome to the world of micro.>
I have been reading about hydroid problems with zooanthids, unfortunately, we were too late in saving it. It smelled pretty bad and didn't look to good.
<Unfortunate... sorry for that.>
But, my question....could this problem have spread to our hairy mushroom?
<If you mean, can it spread nearby and sting, yep. If you mean can it infest the mushroom, then I have to say I'm not familiar with them moving about. I am somewhat inexperienced in the hydroid "field" but in my research ( http://www.wetwebmedia.com/hydrozoans.htm and all links...)I learned that they need somewhat higher concentrations of nutrient to thrive. Also, they are usually "fixed" to the rock.>
It looks good but has a few areas that look similar to the zoanthid.
<Am I missing a past email? What did the Zoo look like?>
  Please help.....
<Trying...
-GrahamT>

Hydroid control? <follow-up> 1/28/07
Thank you for the quick response, Graham T.
<Welcome, though not immensely helpful, I suppose.>
I made an error when I put Zoanthid, I should have put hydroid.
The patch on the mushroom, or I should say on the rock is grayish and looks velvety. The other spot on the Zoo was actually "moving" little things you could barely see. So, somewhat different but I am worried I will miss this and then it will be too late.
<I want to be sure not to mis-diagnose. Is there a chance you could send a pic (under 400K) so I can get a look at the critter?>
OR.....could this be fungus? The rest of my life rock doesn't show any areas like this one.
Overreacting or playing it safe?
<Always playing it safe...
-GrahamT.>
Thanks
Steph

Hydroids infesting my Zoanthids?
Dear Crew,
<Russell>
Here's a new one for me...maybe you also?
<Could be>
Over the holidays my Zoa's (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>

- Choerodon fasciata & little stinging hydroids -
Dear WWM Crew, I have a 240 Gallon with approximately 70 pounds live rock.   On 11-22-02 I added a Harlequin Tuskfish "Tigger" that had been quarantined for two weeks with no signs of parasites or other.  I have noticed tiny Hydroid jellyfish (polyps) on the glass (dots with legs). At first I thought this was a really cool find from the live rock, but a few days ago I noticed spots on the pectoral and tail fin of Tigger, on closer inspection these spots really appear to be the Hydroid polyps.  Can these polyps attack the fish and be a parasite of sorts? <Not attack, per se... but if the fish bumps up against them... sure. But I will just add, as I also have a harlequin tusk, that spots on the tail are not uncommon. They come and go pretty regularly.> Tigger's color is bright and is eating well, and does not appear to be scratching or have any abnormal breathing. <Good deal.> There are not any other fish in the tank.  I am concerned about Tigger's health, the health of the tank, and about adding any new fish until I am sure these hydroid polyps are not going to cause a problem. <No fun... you may want to consider creating a scraper/siphon combination that would allow you to scape off a hydroid and immediately suck it out of the tank. You definitely don't want these floating around the tank. You may need to take more drastic action, I'm sorry to say. Hydroids are a pain - quite literally.> Your help is greatly appreciated!!   
Thank You.  Jen Marshall
<Cheers, J -- >

Removing finger-like hydroids
Stinging hydroids have few natural predators that we can regard as reef-safe. If you have corals in the tank, it may be difficult to avoid manual extraction. In the meantime, you could try a stiff bristled toothbrush tied to the end of a siphon tube so that you could siphon slowly and scrub at the same time. We need to avoid fragmenting and spreading them. Bets regards, Anthony>

- Hydroid Problems -
Hello. <Hello, JasonC here.> How are you today? <Well, thanks for asking.> I have a 55gal. tank set-up for a little over a year with a sebae, two clown perculas, Zoanthid, a hairy mushroom, Sarcophyton, electric star polyps, various sponges (blue, red candy cane, and yellow), a green hard coral, 3 crabs, 8 snails, and a velvet damsel. I have PC lighting 6-65watts, new bulbs every six months whether they need it or not, CPR Bak Pak II protein skimmer and a calcium reactor. All have lived happy and healthy in this environment. About three months ago a friend bought me a sun coral. I quarantined it for three weeks to ensure it was eating correctly and content. I added the coral and three to four weeks later I noticed a lot of "feathers" in the tank on all of the live rock. I am positive it has been identified on your site... hydroids. <Egads.> I tried the siphoning technique but the base is so far into the crevices it reproduced 10 fold. My question is how bad can these things affect my tank? <Well... for their size, they are pretty potent stingers.> I am afraid they are affecting my Sebae. <Quite possible.> He is sitting up but he is not taking the food the perculas bring him. His mouth is open slightly. I feel that if the anemone dies, the perculas will die also. <Not so, they will be fine.> I have to save them! <No worries.> I assume the problem is the hydroids because the sun coral is non toxic. <All corals have the ability to wage chemical warfare.> I have not used any chemicals in the tank since it was formed. I tested the water: 440 ppm calcium, NH 0, pH 8.1 alk Normal, NO3 0, NO2 .05. I am sure the NO2 are just a cycle. What can I do to get rid of the hydroids short of finding a sea dragon, Pteraeolidia ianthina. <Not really that east due to their size - you may have to extract the rocks they are on and remove the hydroids with tweezers.> I have not found a single supplier of them. <The sea dragon? Heavens no... these typically do very poorly in captivity.> If you can think of a single other reason for the eating habits of the Sebae please I am open for suggestions. <Consider more lighting.> My Sebae was a tank split and my tank mimics the conditions it was raised under. <Lighting as well? Most all anemones need intense lighting, and yours is likely not intense enough.> Please help.
--Hydroid Hater-Tonia
<Cheers, J -- >

Threaded Hydroid? 6/12/04
No emergency here, just trying to better understand my tank.
I have a nice, healthy Devils Hand (Lobophytum) that at night puts out one or two relatively long (up to 7 inches) thin fibers that have "off-shoots" about a quarter inch long spaced at regular intervals.  It looks like a tank sized long line fishing rig.  
<yikes... this is not actually part of the leather coral, although it looks like it. I have a strong suspicion here. One of the threaded hydroids. Does this thing look like a barely discernable wisp of a thread... and the "branches" like teeth on a sparse/coarse comb?>
The fibers come out of one of the yellow fingers.  Is it trying to feed or is it a defense mechanism.  If the latter, should I avoid placing another coral within its reach?
<yes regardless... keep all other critters away. And if its a hydroid, watch your arm too... a nasty sting is possible>
Many thanks.  Your site has made a material contribution to my 38 gallon reef's growing success.
<no worries my friend... if this is a hydroid, it can be removed (and future ones can/should be screened by running all new livestock faithfully through a proper 4 week QT). Anthony>

Threaded Hydroid? II 6/12/04
Many thank you for the id Anthony.  I am not worthy of such expert advice.
<we are all on equal footing here my friend... as aquarists we each have our specialties, and we all evolve in time>
I only found one picture on the web that looks like it, the "sparse comb" you so aptly describe.  How shall I remove it? How about cutting off the finger it emerges from?
<no need to cut the leather, just look at the base and see if you can see ho well it is anchored (often appearing like a transparent fleshy plate/base in the case of this type)>
Will it move around the tank if I leave it?  
<not too motile>
After just 8 months with the reef, I am clearly in new territory here... Dan
<its all a learning process... no worries. Enjoy the journey. Anthony>

Stinging hydroids 6/15/04
Hi Guys
<cheers>
Wonder if you can help me. Are there any species of fish or invertebrate which would feed on stinging hydroids? I'm having difficulty controlling them in my tank. Thanks and regards
Adrian
<while there are many fishes and invertebrates that will control hydroids... they are not likely to safe with your other fishes and/or invertebrates (cnidarian feeding Chaetodontids, Asteroid sea stars, etc.). And if you could ID your species of hydroid and find a nudibranch, for example, that was an obligate predator... the nudibranch would soon starve. Your real solution is to get to the root of the problem (excess nutrients) and not focus on the symptom (hydroids flaring). Focus on starving them into submission and then polishing them off with a lite bit of manual control. Improve water changes, be more aggressive about skimming, increase water flow to get excess food/particulates exported rather than lingering to feed the hydroids, etc. Best of luck! Anthony>

Digitated Hydroids
Good afternoon crew,
<Good day>
I posed a question on the forums last week, and no one really had an answer for me. The only suggestion I got, was to email you all and see if you had any good info to share with me. Thank you for any assistance you may provide. Here is the original post from the Marine Invertebrate forum: 
Here is the situation: I currently have 5 of these nasty hydroids (digitated hydroids). Two of them extend to 4in. at night, two of them extend to 3in., and one of them to about an 1 1/2 inches. Of these five, I can reach 3 of them (one large, one medium and the small sized one). The other two are nestled deep into the back of my largest live rock, and there is no way I can get to them. Even if I was able to move all other LR and creatures off of it, they are in deep crevices that are barely wide enough to stick a nail in.
Here is my question (which you could probably guess.. hehe):
Does anyone have good experience with removing these type of hydroids? If so, what was your method? Also, I have had different hydroids in the past, not many but a few, and they generally cycled out within a couple weeks to a month. If you have had them before (the digitated kind), how long did it take for them to cycle out? I wouldn't even mind letting them just do that, except a few of them are getting way to close to some of my corals at night, when they extend themselves.
Current setup:
100g
30g sump/fuge (LV, 4in. LS, macro algae)
AquaC EV180
12x turnover
Magnum 350 canister (changed weekly with carbon)
100lb LV
Test readings:
NH3/NH4, NO2, NO3 = 0
pH = 8.3
Temp = 78 to 80
Ca = 400
ALK = 9 dKH
sg = 1.024
Kent sea salt, 10 to 15% weekly water change, no additives
<Erica, if it were me, I would get a syringe from the pharmacy and make up a strong solution of Kalkwasser and when the buggers are out, inject them with that. It should do the trick. James (Salty Dog)>