AEFW Treatment, How To Get Rid Of Them

Posted on January 16, 2012 | 0 comments

Now that I’m starting a new tank and introducing a lot of new Acropora colonies to my precious colonies, I will thing again how to prevent an AEFW outbreak, because it can be heartbreaking. I will also think about ways to control them in case just a few survive a quarantaine treatment and multiply over the next months and years. In this article I will explain how to deal with this pest, after learning from previous outbreaks and using the latest insights.

Acropora Eating Flatworms or AEFW are flatworms who live as parasites on Acropora corals. In my experiences at least two different types of flatworm seem to affect our Acroporids although others probably exist. I’m not sure if the two types I have dealt with are two different species, or the same species exhibiting two different types of behavior. Of these two types, one seems to be a rather benign species that seems to do harm only when present in large numbers. This flatworm acts as an irritant and the corals hosting it keep their polyps withdrawn a majority of the time. I have never observed any tissue recession, bite marks or egg masses with this particular flatworm. On the other hand there are the larger, more aggressive AEFW that produce a lot of egg clusters and tend to consume the Acropora until it starts to STN at the base caused by stress.
To my knowledge, no in-tank treatment exists that positively eliminates these flatworms and harms nothing else.

The first thing is to find out if your corals are infected and to what scale. Are the colonies full of AEFW, or are there just a few on some colonies. That’s why you have to start with observing the corals closely. Important things to look at are the following;
Does the colonies still have good colors? Infected colonies have a pale color most of the time, without a rich color on base and tips. Most of the time growth is lacking so the tips stop growing and the often distinctive color of the growth-tips disappear. This brings me to the next question.
Does the colony still show growth? Infected colonies often show no growth because they need a lot of energy to repair themselves from the damage that has been done by the Flatworms.
Does the colony show necroses from the bottom up (STN)? This is also one of the signs of AEFW.

If you notice one of these issues and you are sure other factors can’t be an issue (flow, water parameters, fish) the best thing to be absolutely sure you have AEFW in your tank is to dip the corals in TLF Revive Coral Cleaner. I prefer revive over Lugol based products like Tropic Marin Pro Coral Cure or other substances like Levamisole because it is far less harsh on corals.

If you performing a dip following the instructions of the product you will or will not notice “flakes” coming of the colony. These are stunned AEFW, curling up and losing grip on the coral tissue.
Sometimes you will also notice beige-brown egg-clusters on the (dead) base of the colonies. These are the eggs of the AEFW and have to be scraped of completely before treatment. On the base you sometimes notice small “bite-marks”, caused by AEFW eating away coral tissue.

The treatment procedure:

This procedure is based on an out of tank treatment with TLF Coral Clean Revive.

Set up a quarantine tank with decent flow, light and heating. Other equipment isn’t necessary because water changes (with tankwater!) can be done twice a week to keep the parameters in check. This have to be repeated every week for four weeks.

  1. Calculate the amount of Coral Clean Revive you need for the bucket you dip the corals in.
  2. Regularly check the corals for their condition during the treatment.
  3. After 10-15 minutes, gently blow off the corals to remove any possible attached AEFW. Use a small powerhead for this.
  4. Inspect all the corals very well for egg clusters, and scrape them off.
  5. Empty the quarantine tank between every (weekly) dip and clean it out very well.
  6. Fill the quarantine tank with aquarium water, to prevent further stress, and place the corals back.
  7. Repeat weekly, four times until no AEFW or eggs are found anymore.

Quarantine during process of dipping and cleaning the Quarantine tank

Next question, how to prevent future infections and how to keep population in control in case I miss just one of these buggers? There are a few answers to these questions. The first one may be simple, but is is the most important; quarantine! It is useless to dip, treat and quarantine the whole tank following with introducing new corals without giving them the same treatment. Sooner or later you will reintroduce AEFW back into your tank.
Many aquarists have the mistaken idea that you have to spend a lot of money on an elaborate quarantine system. A quarantine system can be a simple 20-gallon tank with a powerhead and a dual PC bulb or T5 bulb. Use water from your display tank for initial setup and water changes. Keep the coral in quarantine for at least one or two weeks. During this quarantine period do a couple of investigative dips with your dip of choice. I would suggest to use Coral Clean Revive because in my experience it is a lot less aggressive towards the corals then Iodine-based dips (like TMPCC). A close inspection with a magnifying glass can also expose some unwanted guests.

Corals just after treatment in Quarantine tank

In case you want to prevent a large outbreak in the future or just for peace of mind; Introduce natural predators of AEFW. There is a lot of debate if Wrasses really can prevent a (large) outbreak, but there are numerous observations known that they really can make a change. Of course (over)fed fish will always choose for “fast-food” (the food we give them). Here’s a list of wrasses you can introduce in your reef to control an outbreak.

Halichoeres Leucoxanthus

Halichoeres Melanurus

Pseudocheilinus Octotaenia

Halichoeres Radiatus, Terminal Phase

Pseudocheilinus Hexataenia

Halichoeres Garnoti, Juvenile

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