Hydroids: a reference to some strategies

[CornishCrustyCorals]

Just a quick update as I was going through the same problem. I added a generic sea hare (Dolabella auricularia) and so far about 90% of them are gone. Actually watched it eating them. There are still some on some of the rockwork where I know it hasn't been as I have a small amount of algae on those rocks also and trust me this thing if it gets to the algae it will eat it. Absolute beast of a CUC soon as the tank is clean I will probably move it to the sump and let it clean all of that and then wait and see if any come back as its the hidden ones that are the problem.

 

[MrStoffel]

Reporting back.
Placed a number of potential predators (see list below) and saw a quick decline until after a month none were visible anymore, and i had 2 different types. Branching and digitate.
I can now say that it was most likely the centropyge acanthops that ate them.
Because after about 6 to 8 weeks i removed the fish because he started bullying my sunburst anthias and blue eyed cardinals. Since then almost 3 months have passed and my hydroid population is back to where it used to be.
I did not change my feeding regime, nor did i introduce a lot of new coral.
All other animals from the below list are still in the tank.
I think i'll add another centropyge acanthops soon, even if he kills off a few other fish, at least i'll remain free of hydroids...

Centropyge acanthops
Coral banded shrimp
Mithrax Crab
Blue legged hermits
Limpet snails

 

[shakacuz]

Just a quick update as I was going through the same problem. I added a generic sea hare (Dolabella auricularia) and so far about 90% of them are gone. Actually watched it eating them. There are still some on some of the rockwork where I know it hasn't been as I have a small amount of algae on those rocks also and trust me this thing if it gets to the algae it will eat it. Absolute beast of a CUC soon as the tank is clean I will probably move it to the sump and let it clean all of that and then wait and see if any come back as its the hidden ones that are the problem.

where did you get the hare?

 

[SaltwaterandLime]

I think i'll add another centropyge acanthops soon, even if he kills off a few other fish, at least i'll remain free of hydroids...

Did you have any damage to corals from him?

 

[CornishCrustyCorals]

Not sure why, whether or not it was actually these things that did it as well but the sea hare stopped going on the rocks where these things are even after clearing out a huge patch of them. This morning I found the sea hare dead.

I am not sure sea hares are the way to go. It seemed to eat them if they were surrounded by algae I guess he just ate everything that was in the area of the algae. This left some in areas which it did not eat before it died.

I have started setting up a small system now. I will be gradually fragging all corals and moving them to it and unless I find some miracle that gets rid of these things I guess the tank will be getting stripped and dried out to make sure its completely free of these things

 

[Uzidaisies]

“Corals hosting symbiotic hydrozoans are less susceptible to predation and disease“

https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2017.2405

 

[MrStoffel]

Did you have any damage to corals from him?

For the time i had him, no.
He did have access to a huge amount of live food in my tank and on top of that he ate frozen very well.
I can imagine some specimens can turn to coral for food when not being fed enough in a young system with little live food.

 

[shakacuz]

Not sure why, whether or not it was actually these things that did it as well but the sea hare stopped going on the rocks where these things are even after clearing out a huge patch of them. This morning I found the sea hare dead.

I am not sure sea hares are the way to go. It seemed to eat them if they were surrounded by algae I guess he just ate everything that was in the area of the algae. This left some in areas which it did not eat before it died.

I have started setting up a small system now. I will be gradually fragging all corals and moving them to it and unless I find some miracle that gets rid of these things I guess the tank will be getting stripped and dried out to make sure its completely free of these things

i have in many places that sea headed do eat them. but it was more specific to the dolabela spp.. i am considering getting one for my hydroids issue as well as as a flurry of bryopsis that has shown up in small patches around my tank. i have done 1 dose of vibrant but don’t believe i will follow through because of my chaeto. i was considering fluconazole as well but want to give a natural attempt to foxing my issue first.

perhaps you got an old sea hare? or one that was already on its way out.

 

[Jaden9933]

Not the best videos but my first. It's a little hard to see but the fringeback nudibranch is eating hydroids. They only eat a specific type as stated by Vetteguy but I am lucky and unlucky to have that type of hydroid.

Do you have any for sale? Mine are becoming problematic

 

[Swayingoceans]

Like many of us, I have had problems on and off over the years with Hydroids. The ones that have always given me the most problems are the common ones that almost look like a smaller and darker version of the beginner coral called Yellow Polyps. But the colonial Hydroid is much smaller than the yellow polyp and glows slightly greenish under blue light. In the past they never got to the point of hurting corals, but more recently they've been proliferating unchecked. So I decided to revisit the basic list of solutions as it appears that there's been no real consensus as what if anything can be done about this. Many have gotten desperate enough to NUKE their tank with a worming agent commonly used in dogs containing Fipronel. Given the porosity of live rock of good quality, once you put a heavy chemical like that in the tank....there will be trace amounts for a long, long time.

A) Lets discuss Fipronel. Its not a bad choice if you don't have a lot of corals and inverts. Many inverts can and do survive treatment...but its hit and miss. Fish can handle it well enough. All worms will die and rot in your rocks...its a wormicide. Its not a very practical solution someone with thousands of dollars of coral at risk. This is why its mainly used in seahorse tanks.

B) Butterfly fish....seems like about a 10% chance of success, but any fish that eats hydroids...might also eat your corals. Plus you would need to quarantine this fish for months to make sure of no Marine Velvet....which is the Black Death in a marine tank where no chemicals can be used and no fish can be caught in net due to coral hiding places. You cant put them in a hospital tank if you cant catch them and traps are often too big to work well in reef tanks.

c) Nudibranchs. Yes...we all know that a Lynx Nudibranch could very well solve this problem....good luck finding one of those! Its impossible. But you can use a common Sea Hare...probably 50% chance of success. There is a lot of wrong information suggesting that these can nuke your tank with ink. However the ones commonly sold by live aquaria and the like don't really have much toxic potential. Maybe a big one would wipe out a ten gallon. But in your large tank its a reasonably safe risk...especially if you have carbon reactor. You will need to provide supplemental algae as these Hares are easily starved.

D) Peppermint shrimp and Emerald Crabs...some eat hydroids and some don't. But I have definitely seen both species consume hydroids. Peppermint shrimp can also eat corals when they run out of hydroids and Aiptasia. but shrimp are easily trapped in a trap you make from a half liter water plastic bottle.

E) Husbandry. For many of us, Hydroids only beomce a problem once we start feeding corals. Most corals get by well enough on sunlight..but feeding makes them thrive. However the same food also makes Hydroid populations explode. Many experts think that one reason you don't want to Nuke your tank to get rid of Hydroids is that they are universally present in virtually every rock, snail, coral, etc we put in our tanks in some hidden unseen form. And they only become a problem once something gets out of balance or some factor triggers things to be favorable to hydroid growth...its not fully understood. So less coral feedings, better filtration--roller filtration is ideal...and possibly even UV sterilizer to knock down free floating life stages of various hydroids.

F) Sometimes increasing Alkalinity and Calcium will somehow make it unfavorable to Hydroids.


Personally, I've found over the years that every fish and shrimp even is as unique as a person....its really interesting but the same species of shrimp you will find ones that hate Aiptasia and the ones that love it. They are just individuals with individual preferences. This is why there is so much confusion over what reef additions will and will not solve your pest problems. Its like throwing a pizza part for kids...some kids won't eat pizza. To get around this...I always add 6 pep shrimps instead of 1 even if its overkill...same with emerald crabs. Eventually every population has an individual with the dietary preferences you require to fix your infestation. For my 100 gallon I added ten crabs and ten shrimp, one sea hare, I increase Alkalinity, I added a UV sterilizer, stopped feeding coral frenzy, installed a roller filter (keeps tank so clean skimmer produces nothing anymore). I don't think this eliminated Hydroids...but my tank went from hundreds to seeing almost none in a month. I'm sure they will come back...just like bubble algae and aiptasia generally find there way back in every few years. Most of the information contained in my article is already in previous posts...I just thought I'd save someone the 2 hours I spend once every few years researching Hydroids...its tough to research as they are one of the most diverse marine organisms on the planet...thus you might have ones that look the same as mine but are not the same at all.

Thank you. You just saved me so much time panicking over hydroids as a complete noob in this hobby. I can't tell you how much I appreciate you taking the time to do this.

 

[drebay]

Really informative thread and much appreciated!! Hoping folks can provide some perspective on treatment. Tanks been up for over 8 mos. Parm not horrible nitrate at phosphate at .12 and alk 8.32. Sorta reluctant to go med route b/c impacting inhabitants. I do have a healthy pod population and had been doing amino’s but stopped with these showing up. Pic shows where droids are on the frag which is POed from the hydroids. Thinking do a H202 dip at 10% peroxide to SW w/ 3% H2O2. Maybe glue over after? Anyways if you have any thoughts on treatment,etc I’m all ears. Went down a rabbit hole reading about this

 

[emmysnewtank]

I had a ton of these popping up in my nano…but dialed back reef energy ab+ and mysis/pellet feedings and they went away starved from lack of food sources.

I only have two fish though and the corals were fine without extra feeding.

back to heavy feeding and they are starting to show up again. Probably go through periods of reduced feeding to manage their population.

 

[jsgraham]

Are these hydroids??

 

[Nano sapiens]

Are these hydroids??

Yes, that's a type of hydroid.

 

[Nano sapiens]

Really informative thread and much appreciated!! Hoping folks can provide some perspective on treatment. Tanks been up for over 8 mos. Parm not horrible nitrate at phosphate at .12 and alk 8.32. Sorta reluctant to go med route b/c impacting inhabitants. I do have a healthy pod population and had been doing amino’s but stopped with these showing up. Pic shows where droids are on the frag which is POed from the hydroids. Thinking do a H202 dip at 10% peroxide to SW w/ 3% H2O2. Maybe glue over after? Anyways if you have any thoughts on treatment,etc I’m all ears. Went down a rabbit hole reading about this

I had the exact same thing on a large colony of Sunny-D zoas a year or two back. Within a couple months the colony had perished, but as is often the case in this hobby it's hard to attribute the death to just the presence of these organisms.

At any rate, if I ever see them infesting a colony again I'll be trying H202 right away.

 

[dannyboy92]

i have early stage hydroids in my tank from what i think to be hitch hikers on coral i received. don't really want to dose meds/chemicals. i've read on a few threads that a sixline wrasse does the job. anyone know this to be true?

 

[Tidal Gardens]

We found that they will thrive when we feed more powdered food and then struggle when we clean up the water.

 

[TangoTang]

This topic definitely needs more attention and user reports.
I myself am battling digitate hydroids. They went from a dozen to hundreds in a few weeks time.
Placed a few potential predators yesterday:
Centropyge acanthops
Coral banded shrimp
Mithrax Crab
Blue legged hermits
Limpet snails

Will report back if any significant effect is observed...

Would be interested in which of these additions you saw tackle the hydroids more effectively? I am also dealing with digitate hydroids and would be interested on your input - thanks

 

[WheatToast]

Really informative thread and much appreciated!! Hoping folks can provide some perspective on treatment. Tanks been up for over 8 mos. Parm not horrible nitrate at phosphate at .12 and alk 8.32. Sorta reluctant to go med route b/c impacting inhabitants. I do have a healthy pod population and had been doing amino’s but stopped with these showing up. Pic shows where droids are on the frag which is POed from the hydroids. Thinking do a H202 dip at 10% peroxide to SW w/ 3% H2O2. Maybe glue over after? Anyways if you have any thoughts on treatment,etc I’m all ears. Went down a rabbit hole reading about this

I had the exact same thing on a large colony of Sunny-D zoas a year or two back. Within a couple months the colony had perished, but as is often the case in this hobby it's hard to attribute the death to just the presence of these organisms.

At any rate, if I ever see them infesting a colony again I'll be trying H202 right away.

A little late to the conversation, but these could also be spionid worms.
https://www.reef2reef.com/threads/id-help-on-frag-boring-spionid-worms.775589/

 

[drebay]

A little late to the conversation, but these could also be spionid worms.
https://www.reef2reef.com/threads/id-help-on-frag-boring-spionid-worms.775589/

@WheatToast was absolutely right in my case. I don’t know if a bayer dip would have helped b/c the hammer was barely hanging on by the time I dipped it. Any case it didn’t make it (ticked bout that) but post mort showed skeleton extremely weak, perforated with multiple tiny holes and what appeared to be or plausible boring spionids. Now to research that topic. Wanted to report back incase someone else finds themselves in a similar position.