Invader

[Freenow54]

#reef squad I have some strange things appearing in my 30 year + tank that I have not had before. One is bristle worms . The other 2 or maybe 3 are a mystery . One I thought was Aiptasia. After buying Berghia and seeing no results to speak of ( 30 gallon / 5 berghia ) I took a closer look at photos on google . Now not very sure what they are ( the green flower topped plants. Then there is the white spots all over the Fiji Rock . Also I see white stringy like tails if you will which

are very visible in one photo. Any thoughts and non chemical treatment ? My Coral are suffering

 

[tbrown]

The "flowers" are hydroids it looks like.

What are your levels currently? Suffering corals in an older tank could be a lot of different things.

Do you do water changes or do you dose?

Any recent additions or changes?

 

[Fish Fan]

I don't know if your tag came through, so just to alert the others: #reefsquad

I agree with the hydroids, and that's about all I've got

 

[Freenow54]

The "flowers" are hydroids it looks like.

What are your levels currently? Suffering corals in an older tank could be a lot of different things.

Do you do water changes or do you dose?

Any recent additions or changes?

Calcium Buffer but that was after this . I do weekly 6 liter water changes

 

[Freenow54]

So what are Hydroids ?

 

[Fish Fan]

So what are Hydroids ?

This article may help:

Beginner Topic  Article 'Hydroids: A reference to some strategies'

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...

• joe2
• Apr 5, 2021
• Updated Jan 9, 2026
• 4 min read
• Reaction score: 45
• Category: General Saltwater Aquarium

 

[jimk60]

I suggest you Google colonial hydroids and check images to identify. This was the worst hitchiker I've ever encountered and killed a bunch of corals before I shut down the whole tank. Don't wait to react like I did

 

[Freenow54]

This article may help:

Beginner Topic  Article 'Hydroids: A reference to some strategies'

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...

• joe2
• Apr 5, 2021
• Updated Jan 9, 2026
• 4 min read
• Reaction score: 45
• Category: General Saltwater Aquarium

I just posted a question in Paul B's thread. As you should be aware I built Paul's vacuuming filter with a 5 micron filter . In your and others opinion if I physically remove the Hydroids with tweezers and brushing while using the filter would the filter trap the fragments and possible " nymphs " or should I let the water run into a pail and replace the water with fresh salt mixed water as I go ?

 

[Fish Fan]

I just posted a question in Paul B's thread. As you should be aware I built Paul's vacuuming filter with a 5 micron filter . In your and others opinion if I physically remove the Hydroids with tweezers and brushing while using the filter would the filter trap the fragments and possible " nymphs " or should I let the water run into a pail and replace the water with fresh salt mixed water as I go ?

I've personally never had hydroids, but from what I've read they can be very hard to get rid of. With that in mind, I'd probably replace the water rather than risk bits and pieces getting through the filter. But again, I've never had to deal with them personally.

Good luck!

 

[tbrown]

I guess it depends on how/where they came from. Sometimes, like algae, things can be in our aquariums and we never see them until conditions are right and they start multiplying. Depending on what they feed on, controlling might be the only option as I'm not sure how to physically get rid of hydroids including all stages.

 

[Freenow54]

I guess it depends on how/where they came from. Sometimes, like algae, things can be in our aquariums and we never see them until conditions are right and they start multiplying. Depending on what they feed on, controlling might be the only option as I'm not sure how to physically get rid of hydroids including all stages.

I have read about it . After 30 + years I guess I have a project now . Paul B says I can't win

 

[tbrown]

I have read about it . After 30 + years I guess I have a project now . Paul B says I can't win

It's not always about winning and losing - sometimes in this hobby it's about maintaining and controlling. Work on figuring out how to control their numbers (probably starting with manual removal).

 

[Rocks reef]

1) Colonial hydroids
2) digitate hydroids (long stringy)
3) Appears to be a vermatid snail infestation.

Oh, you have a TON of bristle worms! I don't think I've seen that many in a tank before. I did once at a LFS that I don't go to anymore, there tanks were quite dirty and had bristle worms crawling everywhere, even in the daylight.

 

[Freenow54]

1) Colonial hydroids
2) digitate hydroids (long stringy)
3) Appears to be a vermatid snail infestation.

Oh, you have a TON of bristle worms! I don't think I've seen that many in a tank before. I did once at a LFS that I don't go to anymore, there tanks were quite dirty and had bristle worms crawling everywhere, even in the daylight.

So what can I do about the Hydroids ?

 

[Rocks reef]

I hope you didn't take my bristle worm comment offensively! I didn't mean that your tank is dirty.

For the hydroids, you can manually remove them. You can also try to use Coral Snow or a DIY snow. It will plug there tubes over time and possibly kill them.

In the first pic, I'd just scrape those off the rock, make sure you get ALL the base!
The stringy things, after looking again, appear to be peanut worms. Harmless.
The last pic with what appears to be vermatid snails, I'd pitch that whole rock or take it out and chisel all them off.

 

[Fish Fan]

I had Vermitids and small army of Bumble Bee snails worked quite well for me. It took a couple of months, but I think they got nearly all of them.

 

[Freenow54]

I had Vermitids and small army of Bumble Bee snails worked quite well for me. It took a couple of months, but I think they got nearly all of them.

What is the problem with Vermitid snails ? They have been around forever

 

[Freenow54]

I hope you didn't take my bristle worm comment offensively! I didn't mean that your tank is dirty.

For the hydroids, you can manually remove them. You can also try to use Coral Snow or a DIY snow. It will plug there tubes over time and possibly kill them.

In the first pic, I'd just scrape those off the rock, make sure you get ALL the base!
The stringy things, after looking again, appear to be peanut worms. Harmless.
The last pic with what appears to be vermatid snails, I'd pitch that whole rock or take it out and chisel all them off.

No Worries I like Bristle Worms Just have never noticed them in this Tank . I have dozens in my second Tank . Again no idea how they were introduced or established . They actually clean around the Coral and eat the left over food . Kind of like a dog at the dinner table. Yup Ugly but maybe stop worse things . I am going to go full bore after the Hydroids , even though Paul B says I cant get rid of them now. Well they were not there before so ...... I am going to scrub them and have a vacuum set up running at the same time . It is a Paul B design . It consists of a pump and filter arrangement . I am going to change the design so the pump sucks water out of the tank then forces it through a filter . I am going to pump the water into a pail and dump it . Then replace the lost water with new. Its going to be a long drawn out process but what can I do ? We will see. Thanks for advice but what's the concern about the snails ?

 

[Fish Fan]

What is the problem with Vermitid snails ? They have been around forever

They are not the worst pest ever, but the biggest issue that I know of is that they spew their mucus web, and if you have enough of them it can cover and possibly smother your corals.