Synaptula hydriformis, Medusa worm invasion

feelingfishy · Jul 30, 2021

Hi, I just recently restarted my 300 gallon tank. I have live rock back from the days when you could actually get live rock. I do not think these critters came in on the rock itself though. Mainly because the tank set fallow for years….. Anyhow there in the tank now. I was just worried about this chemical they release when attacked.

Will This chemical disturb the corals? Or is it just poisonous to fish and other inverts?
btw, I did notice a major boom in there population after vacuuming sand bed.

feelingfishy · Jul 30, 2021

This is the best shot I could get tonight. There are 100s of them though. Sorry for blue it’s late

Goaway · Jul 31, 2021

Medusa is no where near as toxic as the sea cucumbers or sea apples. If you have fish that like to pick on them and you have hundreds. You can probably remove some.

You said your tank is fallow, so.. I don't know who you could have to upset them.

feelingfishy · Jul 31, 2021

Yes, my tank is fishless atm. When I said fallow I meant empty for 2 years. Water was still flowing though. Did not want rock to go completely dead. I restarted within last 80 days. All I have in the tank now is 2 fire shrimp, cleanup crew, and about 23 mixed frags. All is doing well other then 2 days ago fire shrimp freaked out when I put my hand in the tank. Soon I will be adding some basic friendly fish. Was thinking a possum wrasse to keep down on these vermetid snails.

feelingfishy · Jul 31, 2021

Knowing that the Medusa is not very toxic is very helpful though. Do I need to keep constant carbon going though?

Goaway · Jul 31, 2021

feelingfishy said:
Knowing that the Medusa is not very toxic is very helpful though. Do I need to keep constant carbon going though?

Not really if no one is in there to pick on them. Toxins are released with harassment and death. I don't know their lifespan. You may want to remove some before adding livestock. Seems like they were really able to reproduce with nothing going on.

feelingfishy · Jul 31, 2021

Thanks, could of been the fallow period that got them seeded. I never really looked at the tank under strong lights during it. So I could of well missed it. Just seems like they went crazy when I did complete sand vacuum. I would like something to keep them under control though.

Is there any fish or invert that can handle eating them?

Goaway · Jul 31, 2021

I don't believe they have a natural predator. They taste very bad to fish. Manual removal is the best bet.

feelingfishy · Jul 31, 2021

Darn… I just got the rocks the way I wanted them too.

last question, is there any commercial trap you recommend?

Goaway · Jul 31, 2021

These are filter feeders. They pick food up out of the water column. I doubt a real trap will work with them.

feelingfishy · Jul 31, 2021

ok, hopefully they start to dwindle.

Goaway · Jul 31, 2021

I don't know what is going on in your tank to produce food for them to thrive. Maybe some water changes to reduce organics?

feelingfishy · Jul 31, 2021

Over the past 2 months I have done 10+ 20% water changes. 0 detectable nitrates .09 phos. All other parameters over slightly elevated for corals 8.7 alk, 450 calcium, 1400 mag. I have some really thick rocks so I was actually hoping the nitrates would come up to 1 or 2 for the ops and softies.

Edit:Also I have a massively oversized skimmer. The bubble magus b12. It seems to be done with most of the skimming now though. For first couple weeks tons of skimmate but, now hardly any.

feelingfishy · Jul 31, 2021

I am dosing 50ml of Red Sea ab+ every 2 days. For coral coloration. That might be it but, I would like to keep it going.

Goaway · Jul 31, 2021

Well, they aren't hurting anyone. So you really don't have anything to worry about.

feelingfishy · Jul 31, 2021

Ok thanks, I will leave it at that then. They are actually very interesting to me.

Goaway · Jul 31, 2021

feelingfishy said:
Ok thanks, I will leave it at that then. They are actually very interesting to me.

Np, if you ever decide to remove them. They are very sticky creatures and netting them wouldn't be too much of a hassle. Just don't want to injure them in the process. But with no fish or crabs to bother them. I think you're fine letting them be.

I can't say that for 100% you don't want them to be chopped up by equipment.

Critteraholic · Jul 31, 2021

feelingfishy said:
Ok thanks, I will leave it at that then. They are actually very interesting to me.

What I have seen with my worms is that they eat whatever hits the ground. Like fish food, some dead algae, and they have lassoed pieces of substrate and pulled them in to clean them off. It sounds like you had a lot of die-off in your tank over the two years which kept them alive. I believe you're seeing them now because you cleaned in there (sand bed particularly) and they have to come out to find food. So keep an eye on them for die-off, or, you could feed them!