Zoanthids in decline

[Steve Brand]

I've got a 100-gal tank full of LPS and softies which is doing fine except the zoos are languishing. Mg, Ca, carbonate, borate are all good. pH may be a little high at 8.4. Salinity 1.025. No algae, no measurable phosphates.

Doing well: Acans, mushrooms, RBTA, tube anemone, candy canes, leathers, brains, xenia.
Dooing poorly: zoos and palythoas

At times in the past I've had zoa population explosions and also in past similar die-off of zoa.

Any ideas?

 

[paul_111]

I had a similar experience -- a few years of great growth, followed by a complete inability to keep them alive. My tank was zoa-less for about a year. I found a crab a while back and removed him from the tank.

Are they always closed? Did you dip them?

There are many things -- search the forums. They could be irritated by a predator.

I just got some more zoas about 2 weeks ago, and they're fine so far.

Watch them after lights out, maybe you'll see something.

Good luck,
Paul

 

[Steve Brand]

Thanks. I do have a big crab (Sally Lightfoot?) in the tank which I see now and then. I'm sure I could only get it out by dismantling the whole tank. I also have two cleaner shrimp which I think are responsible for killing any clams I put in the tank. I'm thinking of getting rid of the shrimp (easy to catch) and see what happens.

 

[Useful_Idiot]

I went through 4 acan frags before I figured out my peppermint shrimp were eating them. I set a baited trap for them out of a gatorade bottle like a lobster trap and easily removed them. I Also emerald crabs.turn omnivorus after a certain size and sometimes eat zoas, not sure about the light foot though. The fact that its all your zoas and other softies are fine should mean something but I'm not that good.

 

[Zoa Robber22]

i had a similar problem..i would recommend checking your lighting or other nuisances in the tank

 

[DustinB]

I have never experienced a cleaner shrimp eating a healthy clam. I caught my shrimp eating one before and thought they were killing it. After it died I noticed the growth rim was a grey color indicating that the clam had not been growing for quite some time. I purchased 2 clams after that, checking they had white growth rims, and the cleaners won't touch them at all.

As for the zoas, can't really comment on that.

 

[tmz]

I've seen peppermint shrimp, (lystmata wurdemani) rip up zonathus and acans.
There are a variety of pests that can irriate or in some cases consume zoanthus and protopalythoa or palythoa; aterina stars, sundial snails, zoapox, feather duster infestations are a few that come to mind. A dip in Revive and/ or freshwater every few days for a week or two may help based on my experience.

 

[Steve Brand]

I'm going after the Sally Lightfoot crab next. I'd bet that's the culprit, tho I've never seen it chewing on Zoa's.

 

[tmz]

Percnon gibbesi( sallylightfoot crab) are known to tear up corals. I've never kept one but hear tey are hard to catch.

 

[Neroon]

I had what sounds like a similar problem with zoas. I added several small zoa colonies to my aquarium over several years. Each time they would grow for several weeks only to decline afterwards. All my other corals (mostly LPS) and two clams were healthy. None of the zoas ever completely died off, but they certainly weren't healthy. It turned out I had zoa spiders. I found them when when removing a piece of rock with a zoa colony I had given up on.