Star polyps confusing me

[The sea slug]

Hey guys-

About six or seven months ago, I bought a small colony of star polyps. They looked great, and they were doing awesome for a pretty long time. About two months ago, though, I noticed that they were getting sort of thin. The polyps that are there are healthy, no discoloration, but there are way fewer of them, and they have stopped growing. They slowly decreased in number until now I only have four on what used to have at least fifty. It isn't that they just aren't opening, it's that they just aren't there. I tried getting them more light and current, but it isn't working and I'm afraid if I move it to find a better spot (it hasn't attached itself to the rock) it will get stressed and make it worse.

My tank is 37 gallons
Water quality is fine, no ammonia, nitrates or nitrites

I have:
a couple small mushrooms
some zoas
a good-size leather tree
a gorgonian
a frogspawn

three clownfish
a banggai cardinal
three firefish
a yellow clown goby

two nassarius snails
three turbo snails
a few little hermit crabs

I know that there's clearly a problem here, but everything else is happy.
Let me know if you need any more tank info

Thanks!

 

[Dkuhlmann]

Sounds like something is eating them. I don't see any fish or other critters in your list that would eat them. You probably have a hitchhiker of bad sorts. I'd try watching your tank after lights out and see if you can find out what it is.

Bobbit Worm is one of the bad ones that will eat corals but will also eat snails fish and whatever else it can grab. When small I would guess that they eat whatever they can get in their nasty mouth. Hopefully you don't have one of them.

 

[The sea slug]

I know I have a bristle worm-I forgot to mention it. Hope that isn't the problem...those are tough to get rid of!
Would it help if I put up a picture of the coral?

Thanks!

PS-
Do you suppose it might be the hermit crabs? They're supposed to be reef safe, but I do see them up by the polyps frequently.

 

[kinnadian]

Bristleworms are absolutely reef safe and good to have in your tank, their population will grow and shrink based on available detritus to eat. I wouldn't get rid of them.

Do your clowns host in the star polyps?

Is the frogspawn up stream of the star polyps? These have sweeper tentacles that can extend up to 6 inches and sting any coral it can touch.

The polyps aren't attached to the rock? What are they attached to? This is very unusual.

Hermit crab is probably fine.

 

[Dkuhlmann]

Agree the hermit is fine. Even if the clowns were loving the polyps to death and if the neighbor coral was stinging the polyps there is no way that 46 of 50 polyps would just be gone.

Yes it is very unusual and so is the coral eating Bobbit worm. Good God those things are ugly. There was one story about one BW that was something like 9' long and had been living in the rocks. It came out at night and ate corals but also started eating fish and inverts.

Yes the bristle worms are totally safe and good to have in your tank.

 

[sculpin2]

Look for a nudibranch.

 

[The sea slug]

Ok...Kinnadian asked what they were attatched to-good question. I've ended up having to glue them to the rock, because they wouldn't stay. Hang on while I get a photo-maybe it'll be better than me trying to explain.

 

[The sea slug]

Ok, there should be two attachments on here.

The one with the purple rock has the polyps on it on the top left. The other is my tank, just for reference. The light has just turned on here, so not everything is open, but the polyps look much the same either way. Sorry it's blurry.

 

[skeeter_ca]

Gonna need a better picture. Hold the camera against the glass to steady it and let it focus then take the pic.

 

[The sea slug]

Two better photos, coming right up.

 

[The sea slug]

Here we go- and they're awake here, which is probably a lot more useful.

 

[robertifly]

Dude stop while you're ahead I think think they're cute completely covering my wet side overflow box but ........now they have their eyes on total tank domination. Only way I would recommend using them would be maybe on a single rock isolated on the sand bed. Never on rockscape.

 

[The sea slug]

I think they're on the mend- As soon as they got more light and flow for a few days, now they're growing more polyps. Thanks guys!

 

[The sea slug]

Never mind-just went into a death spiral. The purple base is weirdly crackly and there's one polyp left. Phooey.