AEFW or harmless flatworm?

[LuckyInker]

I had noticed some of my acros were in decline over the past few months. At first, it was only prevalent in a medium sized colony and chalked it up to a flow issue (lack thereof) or what I thought was high Alk (12, now at 10.5). So several weeks ago I increased flow by purchasing an MP40w. Since then I noticed other colonies starting to show the same signs of necrosis. Essentially, the colonies started dying from the base up. So I decided to dip them in Lugol's.

And what I found were less than a dozen flatworms. After that dip, I decided to dip my other small colonies and found the same result. I believe the total number of flatworms I had found were less than 20. I thank my Banana Wrasse for that.

So here is my question. Is the illustrated depiction of the flatworms that are coming off of my acros harmful are am I barking up the wrong tree? These buggers are aprox. 2mm in length and swim quite fast while in the dip. Each of them have a tale-tale 'Y' or 'T' marking on their back.

 

[this is me]

If they're on your acros and your acros are not doing good, I'm almost positive that it's AEFW. Bayer is great at getting rid of AEFW.

 

[jerpa]

I agree it sounds like AEFW's. The description you gave is pretty similar to the ones I have seen.

 

[rogerwilco357]

nothing harmless about that critter wiped my colonies out slowly over a six month period took over a year to get rid of them alot easier to deal with when all your sps are gone.

 

[LuckyInker]

Right on. Thanks for the replies everyone. I just set up a quick and dirty QT to rid my display of these guys. I'll be sure to update the thread as this saga progresses.

 

[LuckyInker]

Quick update. I have moved all corals to a QT and have started dipping the acros every other day. The flatworm numbers have decreased substantially as I have only seen three the last two times I dipped. I was able to snap a picture of one during todays dip. The length of this flatworm is almost 3 mm.

Anybody ever see these guys before?

 

[dowtish]

I wouldnt dip your corals that often, you are going to stress them to the point of death. You should only be dipping every 5-7 days IMO, and that also depends on what you are dipping with.

 

[LuckyInker]

I hear ya. While dipping daily with a highly concentrated Lugol's Solution would stress the corals as you mentioned, I have yet to notice any ill effects on the coral in the relatively short time I have been dipping them. In fact, I am now beginning to see more polyp extension post-dip than before.
The idea of dipping every other day is a scary prospect especially given the delicate nature of most Acropora. After doing some research I found that Nikki over at ReefdUp.com was successful at eliminating AEFW using a daily dip. See Method 3.
Not unlike yourself this approach was not taken without a great deal of trepidation. So far the every-other-day approach is working fine for me, however I do plan on spreading future dips out by a few more days.

 

[tang daddy]

Dipping is one thing, have you checked for eggs?

If you miss the eggs there will be a whole slurrey of more soon.

 

[LuckyInker]

Yes, I am continually checking for eggs. It is troublesome that I haven't found any just yet. Typically I let the coral air dry for a minute or two and then I check the base and all the crevices on the exposed skeleton.

 

[rogerwilco357]

they love to lay the eggs on the rockwork if coral is attached check the rocks. Sounds like you might have a fighting chance good luck.

 

[sanchoy]

Qt all your acros. Preferably in small tanks. Dip and observe. At all cost do not reintroduce into the display until a month of no flatworms.

 

[Piper27]

Is it just me or does the picture of the flatworm look completely different than the normal aefw?

No point in dipping your acros more than every 5 days if its aefw, also it's very odd you don't see any eggs. Especially if you had them on multiple corals!

 

[Piper27]

Also you said they swim fast in the dip? That's not a typical aefw if you ask me, mine always curled around and fell off to slowly stop moving and die. Do you have some pics of the corals with damage on them?

 

[LuckyInker]

No, it's not just you. These guys look nothing like the AEFW most people have seen. In fact, it looks more like this one. It too has been identified as an acro eating flatworm. I reached out to one of the biologists working with these types of creatures to try and assist with a positive ID. I have heard nothing yet.

So far both acro colonies that have been affected came from the same LFS in my area. All other acros (added just before I noticed the infestation) were from trades or another LFS. None of these acros are displaying any signs of stress aside from poor polyp extension. And since they all have been in the QT polyp extension has improved slightly.

 

[LuckyInker]

Do you have some pics of the corals with damage on them?

Sure do. The one with the most damage can be found here. It is beginning to make a comeback. Notice there are not tale-tale bite marks as seen with the other AEFWs.

 

[Piper27]

That is crazy, have you noticed any damage to the coral specifically from the flatworm or is it just irritating the coral like a redbug?

 

[LuckyInker]

I can't say for sure that I have seen the flatworms attacking the corals first hand as they are quite small (3 mm or less). I noticed two colonies exhibiting STN and went through a several weeks of tests to identify why they were not doing so well. After dipping in Lugol's the STN would stop and the corals would begin to show signs of growth once again. However, shortly after that: BAM. STN once again from the base.
This tipped me off to the possibility of flatworms. Once I knew what to look for I studied the dip more closely. That is when I noticed those little guys.
At first I thought for sure they were devouring my Acros. However, logic tells me that they could be harmless since I saw no bite marks. None the less, I am taking no chances.

Oh, and I appreciate the attention you guys are giving this post. I hope to not only identify the flatworm, but to also share these experiences with others who may run into them.

 

[LuckyInker]

I heard back from Dr. Rawlinson, a biologist specializing in marine polyclad flatworms. While she would not be able to identify the flatworm without a specimen in which to draw DNA from, she did offer several of her articles to help me understand AEFW better. She also offered to draw DNA from some of my flatworms provided that I supply her with several specimens preserved in ethanol. I am not sure if this is something I want to monopolize her time with unless it helps her current research.
In this article you can see an image similar to the AEFW I have posted above. However, this is not an image of a flatworm, but rather a wholemount of the creature. This does not confirm the flatworms I am seeing in my tank as AEFW.