Treating Digitate Hydroids

[oscarinw]

Today I made a grim discovery. A seemingly healthy small colony of zoas had been dying slowly in my tank. I kept my eyes open for any 'grazer' for about a month to no avail. Today, I noticed a little stringy 'worm' next to the colony. I had seen this type of 'worms' in the tank so I had not suspected it before. On close inspection I realized this 'worm' had a 'sticky' nature. Sort of those you see on anemones when they sting something. I also noticed it contracted and relaxed quite a bit and that it had hair like structures coming of it... more pronounced towards the end. The larger ones are about 2 inches in length.
Introducing the digitate hydroids

All of the sudden it hits me: This thing has the exact reach of the area my zoas colony had disappeared/died. The closest polyp was almost at reach length so I decided to pay attention to it. A couple of minutes later, it barely brushed against the open poly, stuck to it for a brief moment and the zoa closed like its life depended on it. A little digging around this forum and other, I realize it is not a harmless worm as initially thought.
For probably the past 3 months I had noticed it and did nothing to it, just watched it multiply.

Couple of findings of my perusing on the internet:

• People tend to confuse colony hydroids with these guys. They are not the same.
• A lot of people suggest taking the rock out and boiling the rock. Please be careful with this.
• Some people indicate they naturally come and later disappear. In my case, they have been reproducing quite effectively.

One of the people on the threads indicated having treated with 'boiling' water. So that was my method of choice for the just concluded first round of this battle. I used a fine curved tip syringe

Got some RO water to boil in the microwave and started squirting these guys. It apparently works. They shrink and become non responsive and many dislodge its long arm.
I must have squirted about 20 of them this afternoon and there are only a couple left in sight. They are just in areas I can't reach with the syringe.
I also used a different method in about 3 of them that were located in close proximity: Using the syringe, I vacuumed the arm and then pulled quickly so to sever it. I could see the arms inside the syringe. I will keep checking to see if those regrow.
I will report back here with any findings in the future.

 

[Spyderturbo007]

A lot of people suggest taking the rock out and boiling the rock. Please be careful with this.

I'm glad my boiling water injection suggestion seems to be working. :thumbsup:

On a side note, please, never, ever, ever boil live rock. There have been a few people that have almost died or put their entire family in the hospital from boiling live rock.

 

[Sugar Magnolia]

Yes, those things can pack quite the sting.

 

[oscarinw]

UPDATE:
This is day 3: Apparently some of the ones that were treated with hot water are making a comeback. On the other hand, the ones that were plucked still are apparently not around.

 

[cloak]

I've never had any problems with them, they were just there. Eventually though, as the tank matured, the populations declined. GL.

 

[oscarinw]

I've never had any problems with them, they were just there. Eventually though, as the tank matured, the populations declined. GL.

Thanks cloak! I'm keeping busy at trying to remove all these by hand. It'll be hard since I know there must be dozens where I can't see... Hopefully they just disappear like in your case.
One of my cleaner shrimp release its spawn into the tank today. Quite a show. Since I was working hard at catching my digitate hydroids, I sucked a few of the baby shrimp into the syringe. Also in there, there was a dislodged hydroid. And then, a crazy thing happened. The remains of the hydroid caught a baby shrimp and made it put a crazy short fight. Those things are hungry and they mean business even after caught and severed from its base... pretty crazy.
It appears as if the hot water is not a perfectly effective. I still don't see any of the plucked ones come back though.

 

[cloak]

I wouldn't trip... There's more important things to worry about then these "bugs." JME. GL.

 

[oscarinw]

I have been at this battle for about a month now. Out of the past 30 days I have had my hands in the water probably 20 days plucking these creatures from the rock. They are certainly harder to find, but they are there, they come back and definitely pack a stinging punch.
4 nights ago I had almost overfilled my syringe so I decided to remove the plunger and dump the contents of it into the cup I fill with the catch of the day. When I did, some of the water trickled over the palm of my right hand and I immediately thought of their bad reputation. 2 minutes later, I could feel it. Poured some vinegar on it but still felt very sensitive the next day. Sort of when you have a thorn. To the day, that part of my hand is still sensitive.
Some observations on my battle against the digitate hydroids:
1. You have to remove the entire contents of your suction syringe. I noticed that once I started to dump all the water, the numbers seem a little lower.
2. They are resilient. I have seen several come back after what I would have considered a successful pluck.
3. A small number apparently dwindle and die by themselves. There had been a couple that I couldn't get to because of their placement and noticed them gone later. This is almost just anecdotal as many times you won't be able to see them because they 'hide' away for periods of time.

I found a very small one very close to the base of my tricolor acropora and that small portion of the encrusting base of the coral has no polyp extension whatsoever so I'm sure they are even rough on the SPSs.
I will keep folks updated. One month and still fighting.

 

[ohioreef71]

I'm glad to see someone taking a active role in removal. All I keep hearing is they go away on their own. I keep seeing more and of these things in my tank and I want them gone. I wish there was a fish that ate them. I guess I'll be getting a syringe and at least get the ones bothering coral. Too bad some will never be able to be plucked out without rock removal.

 

[nmbeg]

Wow. If it were me, I would tear down the tank--those things look deadly!

 

[oscarinw]

nmbeg, trust me, if I wasn't so fond of all of the rest of the life on those rocks, I wouldn't think twice...

So an update was due.

A month and a half have gone by. The hydroids are still pretty much everywhere. A week ago today I decided to stay back for a while. In just these 7 days I have seen them pop out everywhere. It's disheartening.

For now I will only go plucking if one is dangerously close to one of my corals and hope that eventually they die out of my system. No high hopes though. To think that 6 months ago I could see one or two of them here and there. They're now all over the place.

On a good note, my fish are back in the tank. I own 2 black and white Ocellaris, 2 male McCosker flashers, 2 male Lubbocki fairies, a large Solorensis wrasse and a royal gramma. After 7 weeks of isolation for an ich outbreak and being treated with copper they all did really well in my 30gal tall tank and all but the hippo tang survived to tell the story. They are as chubby as ever.

 

[oscarinw]

FIRST DAY OF DECEMBER UPDATE

The fish don't wan't to sleep in the rockwork anymore. The plucking technique has officially failed. I have a theory about why the are called hydroids. Some places where one was severed, two have come out. Just like the mythological hydra... there's the reason for the name. I'm sure it's a coincidence, but a very frustrating one nevertheless.
Starting today I will try the use of Hydrogen Peroxide. The initial plan is to spot squirt a few hydroids to see what happens. If this proves effective, I will then try to remove a few rocks at a time and dip them in a peroxide solution.
Recommendations are appreciated.

 

[89Delta]

Following as i'm starting to have an issue with them too....grrr....

 

[BlindZide]

I am glad I stumbled upon this. My orange Zoas have been rarely coming out. I noticed what looked like white orbs poking out from around the polyps and much to my surprise, it looks a lot like the first photo but in the shape of an anemone. I know it isn't Aipstasia because it doesn't retract like the ones I have been trying to get rid of. Instead it sticks to my fingers. I pulled the plug the polyps are on out and looked and this seems to be in every nook it can find on the coral. Any suggestions on what to do with this?

 

[Cbsailor11]

I had around 30 of them in my 46 bow. Read that an African Flameback Angel would eat them. I got a Dwarf one(Centropyge acanthops). They have been gone for 3 month now.

 

[oscarinw]

@ blindzide: I think you might have some pseudocorynactis. Look them up. There's some division as to their role. I think their sting is quite potent too. Shine a flashlight at night. They come all the way out at night...

@Cbsailor11: How sure are you that this is the pest you had? And also, do you remember where you read that about the angel? This could be good news for me...

 

[Cbsailor11]

@Oscarinw I'm very sure we it's the same thing. Are yours light sensitive? Mine would retract when hit with the flashlight at night. Is the base triangular shaped?
I will go through my notes tonight as mine was delt with during the summer. I do remember looking here and Wetwebmedia.com

 

[BlindZide]

I looked up pseudocorynactis and no one seems to get rid of them but instead keep them. Any tips on removal? They are cool looking and you are right, pseudocorynactis looks like what I have, but making my corals mad is a big no no and it has to go!

 

[ormet]

oscarinw, i feel your pain. I have lived with them for almost 2 years.

During these 2 years i have done 1 tank upgrade where i only transferred corals and fish and inverts. All corals were at the time dipped for 20 minutes in ReVive.

I have also moved the tank once and during the move i only transferred fish, corals and inverts again.

During the last move, i completely disinfected all equipment, the tank, the overflow and the plumbing using vinegar & boiling water.

I have them still.

I could never totally disinfect my siporax filter media as i used it to jumpstart the tanks both times, but i did have the siporax in fine mesh bags that i changed during every move.

They have during these two years been very numerous or just a few.

C. Acanthops love them. Unfortunately the acanthops cannot reach them in the sump, skimmer, overflow box, under rocks and in certain nooks and crannies.

More unfortunatly still, both my Acanthops have developed a taste for my stony corals and have been returned to the LFS.

Today i have a Pseudocheilinops ataenia that i think keeps them in check.

The hydroids have survived dipping in revive and other coral dips. They have also survived 20 minutes fresh water dip.

Good news eh?

Best of luck to you.

 

[oscarinw]

@cbsailor. They are definitely light sensitive and quite more active during the nights. The smaller individuals sometimes venture out during the day but the larger ones certainly are active only at night. Yours is a great tip. I would hate to have to put a fish that starts nipping at my acros but might be worth the try.

@blindzide. Aiptasia removal methods should be worth considering since they are related.

@ormet. Thanks pal for the quality information. I wish it was different news though. I might give the pink-streaked wrasse a chance. I love wrasses. The problem is I would need to look for where to find it for sale as I don't think it's very popular here in the states. I am very close to considering a fresh restart via acid bathing the rocks and maybe clipping and resetting coral cuts.
Again, tack så mycket!