Exploring a possible In Tank Treatment for the cure of RTN

[cerreta]

I have had a difficult time with Rapid Tissue Necrosis (RTN) of sps corals in the new reef setup. I have lost several colonies to RTN. As I became better at recognizing the beginning of colony infection I have been able to frag off unaffected branches and safely move them to the sump. However, this practice to save a colony results in frags of the original, which is smaller and not as nice looking, of course.

On Tuesday, I noticed my second favorite colony; a 50+ branch Acropora nana had RTN splotches on a few segments of the colony. In recent experience with RTN I have seen signs of RTN, and then the following day would result in ½ colony death. By day three, if no intervention was made, the entire colony would be consumed.

The problem with this infection is the size of the affected coral colony. It is not so easy to frag. So, I decided to try a new approach. I target treated the colony in the tank.

Treatment Regime: 0.5cc Lugols solution mixed in 16oz RO/DI water. Circulation pumps and the return pump were turned off for 15 minutes after treatment. RTN spots on the colony were targeted with gentle basting of Lugols solution from a turkey baster. This step was repeated until all the solution was gone. After a 15 minute quiet cycle the pumps were reengaged. Skimming and use of activated carbon was resumed to try and remove excess Iodine from the water.

Unfortunately on the day after recognizing the RTN infection in one coral colony, two others were observed to be infected too.

So, far the results have been surprising. Today, Thursday, is day three after initial recognition and treatment of RTN. The RTN of an A. species in the nano tank has doubled and seems to have failed treatment. However, the A. nana and A. staghorn have not shown any progressive RTN. It seems to be working on these corals.

Observations:

Day one: Only the A. nano showed signs of RTN. This coral was treated with the Lugols solution in the tank.

Day two: The RTN of the A. nana has not consumed half the colonies like previous infections have done. This was major success since I was unable to remove this coral from the tank. I also noticed some new RTN splotches on the blue-tip staghorn. I also witnessed ¼ of an A. species (in nano tank) colony infected with RTN. I treated all these corals on day two with Lugols solution.

Day Three: The RTN of the A. Nana and staghorn have not shown any significant advancement of disease. Based on previous events I expected the colony to be mostly infected if not completely demolished by this time. Unfortunately, the Lugols solution did not work as well on the A. species located in the nano tank. This coral, day two of the infection, appears to have 2/3 necrosis of tissue. I did not treat the corals today for fear of overdosing.

Conclusion: Based on these observations I am pleased with the results and will continue to monitor the effects of RTN disease in this aquarium. Some words of caution. From previous readings and personal observations, I am aware that the form of Iodine found in Lugols solution is not considered reef safe. In fact, it has been shown to have negative effects on Green Star Polyps (GSP) and related species. Thus far, I have not seen any damage to the GSP colony that I have in this tank. Furthermore, I have not observed any other negative impacts at this time on any of the corals in either tank. It should also be noted that both tanks are part of the same system (Nano plumbed into main system filtration system)

If anyone has insight or suggestions regarding this dosing scheme, I would appreciate hearing it. I’m not convinced that this treatment is safe in the long-term, but I am willing to take the risk, since I am tired of losing corals to RTN. Furthermore, I truly could not remove the A. nana from the aquascape due to its size and fact that it was cemented to the aquascape.
I hope this treatment proves successful. I wanted to share the information in hopes that other aquarists may try treating their infected corals to share the experience. Obviously there are risks involved, but others may find, as I have, that this treatment does offer hope for saving large colonies in a reef system without being forced to remove them from the aquarium, which has consequences too.

 

[Big E]

Good luck with your test, but imo you need to fix what's wrong with your tank conditions. RTN isn't a disease but a result of something wrong with your system.

Find out what's causing the problem instead of treating the dying corals.

 

[panic]

Are you experiencing any temp swings right now?

 

[thebicyclecafe]

You mentioned this was a new tank setup... probably lots of instability involved here, thus the RTN. Acropora, especially wild caught specimens, are extremely susceptible to stress induced tissue necrosis and it's not uncommon for them to lose an entire portion of their flesh, while a small amount remains hanging in there. The remaining portion may remain and grow back, or it may just slowly die away if tank conditions do not improve.
I'm also skeptical that stress induced tissue necrosis can be contagious, other than just being correlated because the tank is going through instability, causing all sensitive corals to suffer. "RTN" isn't a disease, but rather rapid death of the coral due to elevated levels of stress (from chemicals like ammonia, or changes in temperature, pH, alkalinity...)
I'm speculating here, but from my experience Lugol's or any iodine supplement doesn't help an acropora coral that is suffering from stress induced causes (i.e. shipping stress, instable tank parameters)... the iodine does take away bacteria which may be related to the actual tissue necrosis itself, but does nothing to remedy the stress and can in fact increase the level of stress undergone by the coral. In my experience the coral either has a portion survive, or it doesn't, it's a matter of the survivability in the coral itself and not the bacteria the medication is cleaning off.
Then again, I may be wrong so hopefully somebody else can chime in regarding RTN and iodine treatments. I haven't seen an improvement on using iodine compared to not using, for RTNed specimens.

 

[jmcmahon66]

I completely agree with the above comments, and ask that you post water parameters to see if anything is out of order. There is a large amount of hair algae in your photos which means phosphates and nitrates are present That alone could be your problem. IME, RTN and STN do not look like the photos you posted. My RTN events have been base up or branch down, with large sections peeling off. Your photos seem to indicate flatworms with the small sections of removed tissue in the branches. Have you noticed AEFW or small egg deposits on the exposed skeleton? If it were AEFW, then the large doses of iodine solution would probably slow down the death of the coral, but not reverse the problem. HTH Good luck.

 

[clkwrk]

I think if you started with your params that would help ......IME RTN happens when conditions are unsuitable for the acro.......

Your Nana appears to be STN'ing......Just from the looks of the pictures your flow could use some help and you have a nutrient supply somewhere. Or as said possible acro flatworms they are in Arizona.

I will also mention you failed to say you are experimenting with Prodibio. Which it's self can have different effects depending on each different setup.

Also RTN usually is a complete loss of a sps in a 24hr period.When RTN sets in the skin flakes and peels off. With STN it receeds slower and tissue doesn't flake off ect.

 

[cerreta]

The water parameters have been in check. PO4 at .1ppm. Ca 425. Mg and St are within normal limits (can't recall actual values). NO3, NO2, NH4, are all zero. The temps have been elevating to 83-84 during the day, but this has been a gradual uprising, not a sudden swing. The photos have been taken right after treatment, so the water flow is completely OFF. The corals in the main tank have high flow. The coral in the nano has very poor flow come to think of it. So, I will address this issue today.

I have had a bad bloom of hair algae. It is not coming under control. However, throughout this bloom, nutrients stayed at near zero, including PO4 which is usually at .3 or less. I do need to change the Phosban and carbon in the reactor very soon. So, I will just do it tomorrow. This may help get the PO4 back to <.3 where I like it.

Chris, yes I have been dosing Vodka and Prodibio BioTim and BioDigest. However, the RTN I have experienced began before dosing these products. So, I am not so quick to say the products are the cause. However, I have been giving thought to stopping these products and reinstalling a UV sterilizer.

To clarify, the A. nana and staghorn are larger aquacultured colonies that have been in two reef aquariums for over four years. The A. species was a wild-caught specimen and just recently purchased. This coral is completely dead this morning. When I looked at the coral yesterday, I am fairly sure that it was RTN and it did begin at a tip and sloughing of tissue did occur.

As for the staghorn, it too was having RTN with verified sloughing. When recognized, I removed the coral and proceeded to resect the infected branches. The remaining coral was placed back in the tank. The splotch I thought was RTN was not. However, the fresh cut section was treated to prevent a new introduction of the infection.

As for the nana, I do acknowledge the atypical presentation. In fact, I think Chris may be right about this having STN. Furthermore, I do not recognize any flatworms or red bugs of any kind on any corals in this tank. IME I have only had RTN conditions up to this point, so I am not sure how to recognize the STN.

BTW, does the S in STN stand for "slow," "stress," or something else?


I also want to refute some comments made by Big E and thebicyclecafe before people start running off with this fallacy.

RTN isn't a disease but a result of something wrong with your system.

"RTN" isn't a disease, but rather rapid death of the coral due to elevated levels of stress (from chemicals like ammonia, or changes in temperature, pH, alkalinity...)

I am not sure of your sources of information, but I do think these statements are blatantly false.

According to Sprung and Delbeek as stated on pg. 442-446 of The Reef Aquarium Volume TWO:
"...as more aquarists are growing stony corals there... there have been more reports of rapidly progressing diseases that cause coral tissues to disintegrate." Later in the paragraph they state, "The rapid loss of tissue leaving behind a white skeleton is not bleaching, it is death of coral due to a pathogen. It is contagious and can sweep through and kill the corals in an aquarium in hours or days. Hobbyists...have been calling it rapid tissue necrosis, or RTN." They also make this statement, "It is a general opinion (ours included) that most are caused by bacterial infections, but little is known about this."

In the same topic the authors go on to describe a treatment performed by Dr. Craig Bingham with Lugols solution and Chloraphenicol. These treatments were, of course, applied to the corals in a quarantine setup, not in the tank.

This is where I got the idea to try and treat with Lugols solution in the tank.

I consider this information and these authors to be experts about aquarium diseases and do believe what I am experiencing in the tank is RTN of some corals, but maybe some other form of tissue necrosis on the A. nana, like STN or maybe white-band disease. I have to read more on that to be sure. In any case, tissue necrosis conditions are likely to be diseases caused by pathogens. This would confirm the results I have experienced with treating the corals with a powerful antiseptic / antibiotic like Lugols solution. There is no doubt in my mind that if left untreated, these corals would have had the same fate as the wild-caught Acro that I could not save. However, I do acknowledge that it is puzzling why the treatment only worked for two of the three corals. It is fair to suspect that other conditions may be acting here as well.

If you guys (Big E, thebicyclecafe, and jmcmahon66) disagree with this notion, please provide your sources of information regarding your claims, so that I can investigate it further. However, I do strongly believe that you are incorrect.

 

[AcroSteve]

<a href=showthread.php?s=&postid=7824482#post7824482 target=_blank>Originally posted</a> by cerreta
The water parameters have been in check. PO4 at .1ppm. Ca 425. Mg and St are within normal limits (can't recall actual values). NO3, NO2, NH4, are all zero.

What about alk? I think it has the most direct effect on stn events.

 

[clkwrk]

po4 @.1 is not in check .....................

 

[jmcmahon66]

Quote from the Home page: "Reef Central is an online community where quality information about the marine and reef aquarium hobby can be exchanged among all levels of hobbyist from beginner to advanced."

cerreta- Myself and others have proposed hypothetical situations that could possibly be the cause of the disease process you have documented in this thread. I find it pointless for you to resist information that others freely give by presenting their opinion as "blatantly false" and feeling a desire to "refute comments before people run off with this fallacy". While I highly respect the authors you are quoting, there is a great deal of information that is more current than the Sprung book. The last sentence in the quote you provide states " but little is know about this". If you feel you are on the brink of a major breakthrough in treating RTN, then I wish you all the best, but I was dissapointed to read your responses to the posters. Please research the topic and form your own conclusions for the benefit of your marine animals.
Regards,
Joe

 

[Frankysreef]

I myself experienced some STN ( slow tissue necrosis ) because of high alk 11.5-12.. I dropped it to 8, kept calc high, and STN has stopped and corals are now regrowing.

 

[G-money]

RTN could be the result of some type of infection or it could be a shutdown reaction. IMO, it's usually the result of unhappy zoox. They rule the coral, not vice versa.

The great majority of the info on RTN is pretty old. If it were most often bacterial in origin, the treatment would be well-known by now. It isn't well known because it still happens alot and "treatment" brings little (if any) success. IMO, the best you can do is frag completely healthy areas and cross your fingers....good luck!

 

[oddballs]

gotta agree as a shop owner if it starts cut it up. ive honestly never seen a treatment that helps rtn or stn ! if left alone a small portion of the colony may survive but fragging will usually help eradicating the problem and save a larger %of the acro colony just my short 2cents.

 

[Big E]

If you guys (Big E, thebicyclecafe, and jmcmahon66) disagree with this notion, please provide your sources of information regarding your claims, so that I can investigate it further. However, I do strongly believe that you are incorrect.

I was just offering my opinion based on my experiences as a reefer. I could care less what Sprung or Deebek say. Do they post pictures & progress of their reefs daily on this site like hundreds of reefers do?

The so called experts that write books & articles are well behind the curve.

There aren't hundreds of threads aboout coral RTN in this forum. It's not a big issue unless you bring in unhealthy corals or your system is imbalanced.

Like I said.........good luck, but imo it's much easier to fix the cause then treat the symptom.

 

[AcroSteve]

When I was less experienced than I am now and had an STN event, I would frag like crazy and hope they did not die anyway.

Now, I do not frag, I check my parameters and usually stop it in it's tracks after correcting the problem. The corals then can recover and re-grow over the dead areas.

 

[Brad A.]

<a href=showthread.php?s=&postid=7827822#post7827822 target=_blank>Originally posted</a> by AcroSteve
When I was less experienced than I am now and had an STN event, I would frag like crazy and hope they did not die anyway.

Now, I do not frag, I check my parameters and usually stop it in it's tracks after correcting the problem. The corals then can recover and re-grow over the dead areas.

Completely agree with the above.

In addition, 3/4 of the time I've delt with stn or RTN, my alk has been screwed up.

Lastly, IME, my acros tolerate temp swings, pH swings and lighting changes, but when it comes changing alk parms... start dying.

I'd do some water changes, clean out the algae and closely follow the tank params. I'd also rec avoiding the whole tank iodine treatment.

good luck

 

[cerreta]

I did not intend to offend anyone. However, if you make statements that contradict published literature, and you were aware of it, as you claim, than it would be prudent to at least acknowlegde it while offering your opinion. I was simply pointing out that the comments made were conflicting a popular resource. From my perspective the comments were puzzling to me because of an apparent inaccuracy. I would like to read these articles that refute the Sprung book to gather a wider perspective for a possible cure, or correction of an ailment that I have failed to find.
Like learning that alkalinity levels are a major cause of RTN. I previously thought it was mainly a temperature issue.

there is a great deal of information that is more current than the Sprung book.

Joe, can you please tell me where to find these?

I do wish to thank all those for the comments though. I do appreciate it, even though I do not agree with all of them.

Back to task. My alk and Ca are controlled by a Ca reactor. Alk has been in the range of 7.6 to 10.8 in the past two months since startup. The last check was 9.2

Chris, I made an error on the PO4 value. I was going from the top of my head. PO4 has been .03 at startup and last check was .01.
Strontium is 16 and Mg is 1140. pH 8.2. ORP 372.

Therefore, the only water parameter that seems to be out of wack is temperature. Which I think may be my problem. Last week I had temps as high as 86, but this week has been closer to 82. I do have an algae issue, which always seems to plague me when I redo a system with this rock. Could the rock cause algae blooms despite proper water parameters? Does cooler water temps reduce algae growth?

As far as treating the the corals with Lugols, I still can not shake the fact that it worked to stop the progression of RTN or STN, whatever it may be.

 

[clkwrk]

Well you may have seen my post about my losses due to temp.......My tank normally 80-81 that day I came home to 88 over the next few days I lost a toal of 14 or so sps and a clam. It may also have been that temp effected things I can't see and those things inturn had an effect on the sps and clam.

So I won't rule out heat.

 

[Big E]

Salinity is another parameter that can cause issues. Big thing is to get everything stable.

I would stop all that vodka & prodibo for now. If you are going to use prodibo, follow the manufactuer's directions & quit experimenting by using the vodka. Let things stabalize for three months without changing or adding anything.

Just looking at that first pic you posted, I see a mushroom near the base of that coral. It's going to fight for space & try to kill the acro. Any dead spots near that mushroom are probably from that.
In the right bottom corner of the pic looks like aptasia. If it is they are going to sting acros. Macro algae will also fight for space & some corals aren't able to fight them off.

If a coral like in your pic is being stressed already by these pests & you are experimenting with vodka & prodibo, plus having temperature problems, it's a recipe for coral death.

Rid the tank of the pests & problem algae, set up a maintenance plan that works for you & just keep things stable. I'm willing to bet the RTN problems will disappear.

No disrespect to any authors, but as mentioned that info you're quoting is almost 10 years old. A lot has changed since then. There is a ton of info in this forum concerning SPS. Everything mentioned by posters is all there, do some searches.

 

[MiddletonMark]

Lots of opinion on RTN, very little for studies on it - thus the grey area we find ourselves in.

As for another take on RTN, Borneman says `In my own work with Lowrie, we did bacterial platings from more than 400 separate cases of RTN and found no consistent or obvious bacterial population at the genus level' [Borneman + Lowrie 1998]

This [among other stuff] would tend to contradict the Sprung/Delbeek hypothesis.

If looking for an author who is skeptical of the bacterial-infection hypothesis - then he'd be one to consider. Lots of debate and little known in the scientific community on this, in my reading. Others feel that it's all wrapped up ... I guess that's the way this hobby is often