Digitate hydroids

[Fishbird]

My tank is quite new, I’ve only had it set up for 8.5 weeks. Very early on I noticed a white worm-like thing that would come out at night from a hole in one of my pieces of live rock and was very light sensitive. I took a video to my LFS and they identified it as a dorveillidae worm. They said these worms can be both free moving and anchor in place. I’ve seen lots of them popping up, in my sand, from my rocks, from my macroalgae...and just today randomly stumbled across somebody posting about “dreaded digitate hydroids”. I definitely have the digitate hydroids and not dorveillidae worms. I’ve now read a bunch of threads about them including one where somebody here pointed out that digitate hydroid only seems to be a term used in the hobby so the only information about them is from forums like this. Some people say they’re harmless, some say they kill corals and fish. My first fish is in QT right now, and I have some CUC that I’m quote attached to but other than that I would be ok with breaking down this tank and starting over again totally. I could leave my animals where they are now while cycling another tank I have laying around and then switch them over once it was ready. Is this the best solution at this stage in the game? Are these hydroids really not very common or are they in every/most tanks and just go unnoticed because of their light sensitivity?

I did see that some people recommend trying to starve them but apparently they eat copepods and I am trying to build a copepods population in my tank so I’m not really in a place to starve the hydroids.

Are there different species that all fall under the common name “digitate hydroids” with different degrees of stinging power?

I saw people saying they’d tried vinegar, lemon juice, Kalk paste, AiptasiaX, boiling water, peppermint shrimp and manual removal and nothing worked. One person did say they watched emerald crabs eat them but that seemed to be a one off since others said their emerald crabs didn’t touch the hydroids.


thanks

 

[KJ]

Did you have any pic of this Hydroids?

 

[Fishbird]

Here are the best 3 photos out of the 20 or so I just took. They’re really active! I’m hoping you can zoom in enough to see them. They look sort of zig zag until you get to the bottle brush looking “head”.

 

[KJ]

Here are the best 3 photos out of the 20 or so I just took. They’re really active! I’m hoping you can zoom in enough to see them. They look sort of zig zag until you get to the bottle brush looking “head”.

Digitate hydroids.

 

[Fishbird]

I know they are digitate hydroids. (These are easier to identify for me than “normal” hydroids vs Aiptasia. Thanks for helping on my other thread!)

like I said in my initial post, do they sting corals and fish? Since my tank is so new is starting over the best thing to do?

 

[Beau_B]

I recently discovered I have them too. I don’t have a plan for management yet, I’ve been trying to tweezer them out when I can...

I haven’t had any issues regarding damage to fish/inverts/coral, but I don’t have a lot of sensitive coral either.
Not much help, other than you aren’t alone. No idea where mine came from, just appeared post dino stage, 6+ mo tank age.

 

[ScottR]

I know they are digitate hydroids. (These are easier to identify for me than “normal” hydroids vs Aiptasia. Thanks for helping on my other thread!)

like I said in my initial post, do they sting corals and fish? Since my tank is so new is starting over the best thing to do?

If you start all over, you’ll probably end up with them again. They’ll most likely go away over time. Just leave them be.

 

[GreenreefSC]

I used to have a ton of these when my tank was about 6 months old. After about the 1 year mark they disappeared on their own and I've never seen one since.

 

[DoctaReef]

I

Here are the best 3 photos out of the 20 or so I just took. They’re really active! I’m hoping you can zoom in enough to see them. They look sort of zig zag until you get to the bottle brush looking “head”.

I have them too... what did you do about them?

 

[Fishbird]

The honest answer is that the hydroids (and an Aiptasia) completely changed the direction of my tank. I’d been quarantining everything wet, except, the original pieces of “live rock” that came out of tanks with fish/corals/mobile inverts/the works at one of my LFS. It was the CaribSea rock or something along those lines. Right when I was reading about digitate hydroids and finding the Aiptasia I was also learning about aquacultured live rock from Florida. I essentially started my tank over with that rock. I’ve had/have some pests but I have a lot of cool stuff too. I figure if I was going to deal with pests anyway, may as well get the cool things too!

 

[andrewey]

I wrote this in another thread, but every time digitates (and most colonial hydroids for that matter) are described in a post, someone inevitably suggests they might be able to sting corals because of their effect on seahorses. Personally, I wouldn't worry about it- if you go searching, while this theoretical tidbit is often repeated, I was unable to find a single reference on this forum or RC to anyone actually experiencing any coral damage from these guys. At this point, I assume they're perfectly safe in a reef tank and most will go away on their own in time.

 

[PP123]

My advice is not to worry about them.. I have some digitate hydroids in a mixed reef with mostly Hammers, Ducans and other LPS... some zoas and i find they don't bother or irritate any corals and definitely won't bother your fish.

They mostly come out at night and not visible during lights on.. I tried removing manually at the start and just stopped and relaxed.. they are just part of the reef!!

My Hammer corals do visible damage to any nearby corals that aren't euphyllia but i don't go ripping them out..

Anyway I do have a less visible pod population... so they do probably reduce those numbers..

 

[Beau_B]

Mine are still present. Removing them seemed near impossible. I have other things to worry about. Population is stable, not over running the place.

 

[DoctaReef]

The honest answer is that the hydroids (and an Aiptasia) completely changed the direction of my tank. I’d been quarantining everything wet, except, the original pieces of “live rock” that came out of tanks with fish/corals/mobile inverts/the works at one of my LFS. It was the CaribSea rock or something along those lines. Right when I was reading about digitate hydroids and finding the Aiptasia I was also learning about aquacultured live rock from Florida. I essentially started my tank over with that rock. I’ve had/have some pests but I have a lot of cool stuff too. I figure if I was going to deal with pests anyway, may as well get the cool things too!

Unfortunately, in my case, starting over is not an option- I have too much invested in fish and coral.
The good news: I might have found a good control option, giving support to other anecdotes: Peppermint shrimp and Halloween hermits.
I have a frag system connected to my tank, 30 gal, and added 8 peppermints and the crab. Within 48 hours 90% Of the hydroids were gone.
I took it a step further: Two days ago I removed a small rock with some Rasta Zoas that were getting beat to hell by the hydroids... 48 hours later, the rock appears clean. The Halloween crab spent a lot of time on it today, and though I can’t see the Peppermints do at night, there’s none on it that I can see. I plan on confirming when the lights go out.

If it works, I’ll be happy. I purchased Fenbendazole to kill them all, but this is much easier...

 

[Igor Machado]

Unfortunately, in my case, starting over is not an option- I have too much invested in fish and coral.
The good news: I might have found a good control option, giving support to other anecdotes: Peppermint shrimp and Halloween hermits.
I have a frag system connected to my tank, 30 gal, and added 8 peppermints and the crab. Within 48 hours 90% Of the hydroids were gone.
I took it a step further: Two days ago I removed a small rock with some Rasta Zoas that were getting beat to hell by the hydroids... 48 hours later, the rock appears clean. The Halloween crab spent a lot of time on it today, and though I can’t see the Peppermints do at night, there’s none on it that I can see. I plan on confirming when the lights go out.

If it works, I’ll be happy. I purchased Fenbendazole to kill them all, but this is much easier...

Thank you for you report. I'm facing digitate hydroids and were about to begin Fenbendazole treatment. But I'm start thinking to use biological control. I've read on other thread that coral banded shrimp also works against digitate.

Anyone else with similar experience in control digitate hydroids using shrimps or fishes?

 

[DoctaReef]

As a matter of update, my hydroids are not gone, but under control... I credit the inverts still.
I will say I started dosing vibrant to deal with bubble algae and think that had an effect as well. I’m not sure If it reduced the particulates, live or dead, in the water and starved them a bit.
Either way I’m more focused on management than chemical eradication at this point.

 

[Jevans1000]

Fish fenbendazole works... I was overrun with then my zoas were getting straight up harrassed and hadn't opened for like a month. I treated about a month ago and it wiped them out however I just saw two small ones today a month after treatment

 

[DoctaReef]

Fish fenbendazole works... I was overrun with then my zoas were getting straight up harrassed and hadn't opened for like a month. I treated about a month ago and it wiped them out however I just saw two small ones today a month after treatment

I don't doubt it works... have you had any other long term effects?

 

[vetteguy53081]

They are capable of stinging nearby coral. best recourse is to starve them by preventing any food to reach them. Ypu can also Pluck them out with tweezers, careful not to drop any and . . . BE QUICK as they will quickly retract.
Use fenbendazole if you have many. They will vanish within 48 hours

 

[commanderwho]

I used to have a ton of these when my tank was about 6 months old. After about the 1 year mark they disappeared on their own and I've never seen one since.

Just wanted to ask about an update? Still have any? My tank is about 7 months and now I have some in my tank. Thanks