RTN Parasite ID and Solution

acropora123 · May 6, 2022

I’ve had an issue with a parasite associated with RTN of Acropora palmata and cervicornis in my reef tanks. They seem to infest the corals especially after microfragmentation or any other stressors. I have removed dead corals and cut off the “infected” areas. I have also tried various treatments such as Levamisole and Brightwell frag recovery dip.
After further research it looks to be possibly Philaster Lucinda or Guamense. If anyone has thoughts on what this may be or any solutions I would love to get advice!

GoVols · May 7, 2022

@jda

Can you pin this down?

jda · May 7, 2022

I have not researched this in a long time... not since that snake oil RTN dip that did not work where the makers charged several hundred dollars a bottle, made a bunch of promises that did not hold up, argued with a bunch of people and it did not work.

First, do you have actual A. Palmatta and A. Cervi that is dying, or just the protozoan that is often studied on them? If you have actual A. Plamatta and/or A. Cervi, then I would contact some of the people studying and trying to farm it in Florida. None of us should have any experience with A. Palmatta unless under very special circumstance.

I am generally under the opinion that the protozoan phialster is just an opportunist that comes in when a coral is already dying or dead. I have seen some claims that the protozoan is the cause of all RTN and that no corals can survive it, but this is not even close to true since everybody has had a coral or two RTN and the rest are fine.

If I had to guess, if I put some of those dead frags in my tank, all of my acropora would be fine and the protozoan would not be able to take hold.

If you think that the protozoan is likely to blame, then something like metro might be better, but I do not know. I just remember reading about it. A search would be needed to even try and find a dosage amount or anything. Metro has been used a bit in Tridacna for Perkinsus but too much kills the clam's zoox, but some claimed that it worked. My guess is that too much metro would kill the dinos in the corals too, but this is just a guess. You can find some posts and articles on metroniazadole and corals but I would really be cautious about who you want to believe.

If you are trying to farm A. Plamatta, then I would really like to hear more. It is a dream of mine to one day have a frag of this and to be able to propagate it for others, reintroduction, study or something to be helpful. I know that it will likely never happen, which is why it is a dream, but I am still always curious.