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FAQs about Stony Coral Health/Disease/Pests: RTN
Rapid Tissue Necrosis

Related Articles: Coral Pests and Disease; pests, predators, diseases and conditions by Sara Mavinkurve, Quarantine of Corals and Invertebrates, LPS Corals, True or Stony Corals, Order Scleractinia, Propagation for Marine Aquarium Use,

Related FAQs: Stony Coral Disease 1, Stony Coral Disease 2, Stony Coral Disease 3, Stony Coral Disease 4, Stony Coral Disease 5, Stony Coral Disease 6, Stony Coral Disease 8, Stony Coral Disease 9, Stony Coral Disease 10, Stony Coral Disease 11, Stony Coral Disease 13, Stony Coral Disease 14, Stony Coral Disease 15,
FAQs on Stony Coral Disease by Category: Diagnosing, Environmental (Pollution/Poisoning, Lighting...), Nutritional, Social (Allelopathy), Trauma, Pathogenic (Infectious, Parasitic, Viral) Predatory/Pest, Treatments 

Euphyllia <RTN>, Percula Clown <Aggr. beh.>– 04/10/12
Dear WWM,
<<Greetings Bryce>>
I currently have a 55 gal. It is a reef tank with LPS corals.  Livestock: 1-ish Bubble Coral, 7-8 Duncan Corals, 1 Serpent Star, 1 Pencil Urchin, 1 Pin Cushion Urchin, 1 Four-Stripe Damsel,
<<Can become a “terror” as it matures>>
1 Yellow Watchman Goby, 1 Tiger Pistol Shrimp, 1 Percula Clown, 1 Scarlet Shrimp, Several Turbo Snails, Hermits, and hundreds of Pods. One of my Duncan Corals about a month ago began to develop some bumps around the base, since then the bumps have developed into new polyps. However, my Bubble Coral was not doing as well one month ago.
<<Do make sure its placement does not provide lighting that is too intense…a common mistake with this coral in my estimation>>
It had RTN and lost about 50% of its mass. Now it is starting to come back a bit but I noticed something strange. Some areas of the skeleton never really lost tissue but were no longer connected to the main part of the coral. These two or three areas now have small bumps that have formed in a circular pattern with what appears to be a pin hole in the middle.
<<Mmm, yes…often a reaction (survival response) to stress>>
Is this going to form a new coral?
<<If whatever caused the original complaint is gone/has been corrected, likely yes>>
Can it be separated from the rest of the coral? There is ample space to cut it off.
<<You can…though you might want to wait a bit and let the “babies” become a little better developed>>
Do they need fed anything specific?
<<Small meaty foods like Cyclop-Eeze, Mysis, etc.>>
I feed with mashed/pureed fish and Kent Zooplex. What else would be useful?
<<As stated>>
I also have a Percula Clown. He was wonderful and not at all afraid of hands. I used to feed him by holding pieces of fish between my fingers. He always would be waiting for me at the surface of the water but now has developed a nasty habit. He now will bite my hand whenever it is in the tank.
<<Only fish I’ve ever had to draw blood, was a clownfish>>
Is this due to the food he expects or is it defending a certain patch of rock?
<<Likely becoming more aggressive/territorial with maturity…not uncommon>>
Also, I would like to add some small schooling fish. I was thinking about Blue-Green Chromis.
<<You’ll have better luck with a small social Cardinal species…especially in this size tank.  In my experience even the so-called “peaceful” Chromis will whittle down their numbers in all but the largest systems (hundreds of gallons)>>
I was going to get about 5 or so.
<<The number should be fine with the right species selection…though the Damsel may prove problematic, as already intimated>>
The tank however, is open top. Would they be likely to leap to their deaths?
<<Any fish harassed by tankmates may “leap” in an attempt to evade>>
I had Firefish Gobies that despite the reassurance of the store leapt.
<<Maybe caused by the Damsel/Clown>>
I was thinking something that is going to be easy on the system, school well, yet still be pretty.  Any other types of Damsel/Chromis/whatever else that would work well for this?
<<Do some looking/research re the Cardinal species available to the trade>>
I hope you have the best week of your life!
<<And you!>>
Thanks for taking time to deal with my pathetic lack of knowledge...
<<But improving all the time, yes?  EricR>>

White spots on Montipora capricornis: RTN\Brown Jelly Disease. 4/9/2010
<Hi Tom.>
I have attached an image of my orange Montipora capricornis.
<I had one similar, as well as a purple rimmed variety.>
It has been doing wonderfully since I got it a few months ago, and has grown to about 6 times the original size.
<Mine were growing well also.>
In the past 2 or 3 days, it has begun to develop white spots on it that are spreading fairly rapidly and now appearing in other locations on its top surface.
<Same thing that happened to mine. It isn't bleaching, that is tissue death\Brown Jelly Disease.>
I have inspected for Nudibranchs but have found none.
<Not Nudibranchs.>
This is the only coral in the tank that appears to be having any kind of problem.
<All of my LPS and Softies were not affected.>
All other SPS, LPS and soft corals are doing very well. Even two Goniopora have been rapidly growing for over 3 years. (Funny... I refused to buy them at the LFS, but a co-worker persisted so I reluctantly agreed as long as they paid for them. Its now years later and they are at least 10 times the size and have encrusted onto multiple other rocks. No idea why, but I have had great luck with these, but back to the matter at hand...)
<Congratulations, Goniopora are not easily kept.>
The tank is 135g with 40g refugium/sump.
Fish load is light. 3 damsels, 1 Blue tang (4"), 1 Scopas tang (3"), 1 Banded Cardinalfish,
1 Watchman goby, 1 Blue-spotted blenny, 1 Ocellaris clownfish, 1 Six-line wrasse.
<No culprit there>
I do 25% water changes monthly like its a religion (last change was exactly two weeks ago), and I run 3 bags of charcoal in direct flow in my refugium to combat allelopathy, changing one at a time. Skimmer is an AquaC EV120 that skims about a gallon of skimmate a week. Also running is a phosphate reactor. I grow and harvest Chaeto in the refugium.
<All sounds good there as well.>
In short, everything is going wonderfully beyond my wildest dreams. And now this problem just popped up in this one coral.
<This took out a large number of Montis in my local reef club>
Do you think that it is a Nudibranch infestation that I'm not seeing?
The only other thing I can think of is that its close to time to change my bulbs.
I run two 250w MH lights and change the bulbs every year.
Its been a year and a week. Would such a rapid development of these white spots seem like it would be caused by
old bulbs?
<No, Old bulbs or the wrong light would show bleaching all over, not in spots. and you would see a reaction in your other corals as well.>
Please let me know if you would like any more info from me.
<Water parameters are always helpful. However, if everything else is going well, I'm sure yours would not reveal any 'smoking guns'. >
<Do read here: http://www.wetwebmedia.com/corldisart.html
and do a Google search on the site for Brown Jelly Disease. This 'disease' kills and it kills quickly. It seems to start by a small, insignificant injury and spreads rapidly from there. As it spreads, you will start to see a brown or tan goo floating above the coral. I was able to save a piece of each of my colony by fragging a healthy part of the coral furthest away from the infection and keeping it in another tank. You can try sucking up the goo with a turkey baster and getting it out of your system. Unfortunately, it did not work for me. I also tried applying a dilute Lugol's solution directly on the coral using a pipette. About the only thing I did not try, as it was impractical, was removing he rock the coral was attached to a hospital tank and treating with antibiotics, though that could kill the coral just as quickly as the disease can.>
I appreciate the work you guys do there immensely, and I can certainly say that the point when I found wetwebmedia.com was the turning point in the hobby for me.
Thank you for being you.
<Thank you for the kind words and the best of luck in treating this.>

RTN Theorizing 12/24/08 Hi Crew, <Hello Jason. Minh at your service.> It's been a long time since I've had to write you with a problem. That's good! Unfortunately, one of my beautiful and large Birdsnest just underwent rapid tissue necrosis (RTN). It happened frighteningly fast; in less than a day the grapefruit-sized coral went from healthy to half dead! <I'm sorry to hear about your loss.> While my particular cause is unknown (I suspect encroaching mushroom corals, but unsure), I noticed something interesting. The death progressed along the branches of the coral, not simultaneously. In fact, it spread from base to tips (oldest to newest growth). I understand this is a common pattern. In an attempt to save as much as possible, I broke off branches that were still alive and discarded parts that were totally bleached. <Rapid Tissue Necrosis (also known as apoptosis) is a cellular reaction in corals initiated by various stresses such as bacterial infection, temperature, UV radiation, allelopathy, etc. In this particular case, the encroaching mushroom is a very capable culprit.> More interesting: the frags that had some dead tissue still on them proceeded to degrade in the same manner. Those that were comprised only of living tissue appear OK. <If the tissue on a fragment is undergoing apoptosis, it will continue to degrade until the fragment is dead. I would suggest for you to quarantine any remaining healthy fragments in a separate tank to isolate the cellular reaction. This would allow for the highest survival rate of your Seriatopora guttatus while reducing any risk of exposing other healthy SPS corals to this condition.> This is very puzzling. If this condition was caused by a biological or chemical agent attacking the coral flesh, one would expect that it would either be localized (killing a small area) or all over (killing patches at different places on the coral simultaneously). The fact that the progression moves very predictably along the branches implies, at least to me, that it is innate behavior of the organism, not the result of attack. Perhaps it is an evolved survival mechanism; a last-ditch effort to abandon the skeleton and grow anew somewhere else on the reef more amenable to the coral's health. In our tanks, of course, that would not happen thanks to lots of factors, but possibly on the reef? This may explain why the frags without dead patches survive: the signal to eject never reaches them, so they persist. Do you know of any research in this regard? Thoughts? <Although I have seen broadcast reproduction occur in a similar manner, and some rare instances in captivity, the behavior of tissue necrosis appearing in a predictable band pattern indicates a classic case of apoptosis. This cellular reaction could be triggered by allelopathic attack from a neighboring soft coral. Further reading on this subject is available in an excellent article by Eric Borneman, "The Coral Health and Disease Consortium: New Information on Coral Disease." Link: http://www.reefkeeping.com/issues/2002-03/eb/index.php.> Thanks! Happy Holidays! Jason <Likewise to you and yours. Cheers, Minh.>

Question For the WWM Team. SPS RTN and Diatom growth... cause/s? Allowance/s? 6/11/08 Dear WWM Staff, <Justin> Your website has been a great resource too me and would like to thank you for your contribution to the hobby through this website, it is invaluable. <Glad you find it useful> I started in the hobby one and a half ago with a 12 gallon Nano that was very successful. Six months into it I did my research and upgraded to a 70 gallon system. My current system setup is as follows: Equipment 50g Clear for life pentagon corner acrylic tank with a back corner overflow box. The top front corners are drilled for the two returns, which is powered buy an in sump Eheim 1260 generating a 10x. I installed a closed loop by drilled the bottom right hand side of the tank for intake and the bottom right for the split returns. (see attached illustration 1). <None of these came through. Must be attached...> An external Poseidon PS3, generating an estimated 18x turnover, powers the closed loop creating a circular closed loop flow. I run a VorTech pump in an opposite position to the closed loop at half speed in reef crest mode creating turbulence and an additional 35x. I have a JBJ 1/10th Titanium chiller running in the well ventilated attic directly above the tank that is powered by an external Poseidon PS1, generating an estimated 8x turnover, and returns to the main tank. The lighting is a PFO mini pendant 250 MH running a 14,000K phoenix bulb, replaced last month. I run a 24' 65W, retro fit SunPaq PC actinic bulb and a set of two Current USA moon lights. I recently switched from an ASM G1 skimmer to a Tunze 9010. My sump is a custom built 20 gallon with a built in 3g refuge where I keep 5 lbs of miracle mud and Chaeto under a low watt bulb 24/7. <Stop! I would not have the lighting on continuously here. Chaetomorpha needs a dark phase... I'd arrange the light to overlap, be on when the main display lighting is cycled off> The overflow splits into two where 75% of the flow ends up in the skimmer side of the sump and 25% ends up in the refuge. I run a PhosBan reactor with Eco-Phos connected to a MaxiJet 400 that pulls from the skimmer side of the sump and returns to the return side of the sump. I do not run a heater as the house is maintained at 74º and in combination with the MH I have been very successful in maintaining a stable temp of 77º. Current Parameters -- Very stable. Temp 77º Salinity 1.025 pH 8.3 Calcium 450 Alkalinity 10 Magnesium 1350 Nitrates 0 Nitrites 0 Phosphates 0 <Mmm... I'd read a bit re the need for soluble phosphate... your system, with the reactor, may be too "clean" for the livestock's good> Ammonia 0 Maintenance Schedule I change 10% weekly using Reef Crystals, but recently switched to Reefer's Best. <The ZEOvit product> All sponges are removed from the skimmer, pumps, PhosBan reactors and cleaned out, to ensure no phosphate built up. I dose B-Ionic and or DT's new CA/Alk/Mag chemical additives. I dose a little Potassium (explanation later on) and Eco-Systems trace minerals. I run carbon for 5 days a month. I test all water parameters every Sunday at 8pm using Salifert test kits. Feeding Schedule I feed sparingly once a day and or every other day. I feed with Rod's Food (http://www.rodsfood.com/). Bio Load 1 Med. Yellow Tang 1 Dusky Jaw 1 Blue Chromis 2 small Clown fish 1 Royal Blue Tang 1 Small Six-line Wrasse 1 Peppermint Shrimp 1 Emerald crab Large cleanup crew (no stars), snails, (Hawaiian Trochus Grazers, Hawaiian Turbo Grazer, Micro Hermits, Blue hermits, Strombus Grazers conch, ninja, Pinky Cuke, Hawaiian Littorinid Grazers, Astraea, Nassarius) Natural Filtration I have about 50 lbs of live rock and 30lbs of live sand. Light Cycle Moonlights off 7am Actinic on 11am MH on noon MH off 9 pm Actinic off 10 pm Moonlights on 11pm Issues I have two ongoing issues that I cannot seem to resolve. 1) Diatoms -- (one year later) 2) SPS RTN/STN <This both may well be due to the lack/absence of HP04...> I went through a very patient cycle and waited and waited. However I still to this day suffer from Diatoms. I have done everything listed on WWM site and more I have done two days of darkness, however they always return and are very prominent on the sand bed. They are densest by my Dusky Jaw, as assume it's because the snails get used in the construction of his burrow and hence they stay away from him and the sand does not get mixed up in that area, however the rest of tank still suffers from bad diatom blooms. I can keep pink and green Birdsnest that grow thick branches and have wonderful plop extension and color. However, I cannot keep any other SPS. Monti's die by STN/RTN within weeks and never show signs of growth. I started adding potassium as the ZEOvit system promotes it and I had run out of options. I acclimate slowly via the drip method and place the coral low in the tank and slowly raise up towards the light as to not light shock the coral. All other forms of corals start to loose their tissue and then the diatoms start to attach and I inevitably loose the coral. (See illustration 2) I have recently increased the weekly water changes to 15% and switched salts from reef crystals to Reefer's Best to address the low potassium issue as tested by a ZEOvit user. <K presence/concentration is rarely a rate limiting factor> Other Info The only piece of equipment that I did not buy new was the tank and it was used as a freshwater system. My build thread on sdreefs : http://www.sdreefs.com/forums/showthread.php?t=25429&highlight=50g+build Illustration 1 Illustration 2 Illustration 3 <Again, these graphics didn't make it> Kind regards, -- Justin A. Hai <I'd pull the Phosban out... run this system for a few weeks... see what happens. Bob Fenner>
Re: Question For the WWM Team. SPS RTN and Diatom growth... 6/12/08
Bob, <Justin> Thank you for your email... I do have a follow up comment to your "system is too clean" suggestion. <Ok> I ran Carbon in the Phosban reactor 24/7 prior to MAX in Orange County. I met Mike Paletta who suggested that I run carbon 5 days a month and run Eco-Phos in the reactor instead. The point here is that I was not using a phosphate remover prior to MAX (April 5th 2008) and the issues were the same before installation of the Eco-Phos in terms of diatoms and SPS RTN. <I see> Is it feasible that it could be the opposite in terms of high organics in the tank (except when the corals are dying fast, in which case I'd suspect acclimation, toxins in the water or some other acute problem, but I think we can rule that out). Keeping in mind that the test kits we all use don't detect all phosphates and don't detect bacteria levels at all - Salifert = 0, Hanna = 0.13 Kind regards, -- Justin A. Hai <Mmm... am on to my default general resp.: Perhaps allelopathy... Please read here: http://wetwebmedia.com/cnidcompppt.htm  and the linked files above. Bob Fenner>

Coral eater 2/24/08 Hi, Yesterday I didn't feed my tank for the night and by today morning, I lost half my frog spawn. The frog spawn was 100 bucks. Can you tell me how to catch the predator or can you point to a list of predators for reef? Any help would be appreciated guys. <Are you sure the coral isn't just dying? Hermits can be predators when they get hungry enough, but I'm not sure how likely it is that they'd eat half a coral colony overnight. And most things that eat coral you would have likely witnessed already (especially if it were consuming so much so quickly).> Regards, PraKash <Best, Sara M.>

Re: Coral eater -02/24/08 Hi Sara, Thanks for the quick reply. If the coral was dying how could it have died so much over night? <It's quite possible. It's not unusual for corals to suffer something called "Rapid Tissue Necrosis" or "RTN." Once they get this, they can completely die within less than 24hrs. Here's some more info on the condition: http://www.reefs.org/library/article/rtn.html > I have removed 6-7 hermits from the tank 2 weeks ago thinking they were the predators. Can long nose hawk, sail fin tang, Anthias fishes be predators? <highly unlikely> If the coral was dying what could be the cause? Ca 500PPM, 11dkh, 8.2 Ph. I have never checked for Mg. Can you please help? <Oh geez, it could be a lot of things. What is your salinity, temp? It could simply be the shock of being in a new tank if it wasn't acclimated slowly enough. How old is the tank? Are there any other corals near the Euphyllia? Btw, unless this is a rather large colony, $100 more than I'd pay for this coral.> Regards, PraKash <Best, Sara M.>

RTN Question -- 5/25/07 Hello and happy Friday,   <Hi there and happy Saturday!> I have a couple of questions regarding RTN.  Can RTN spread to other corals?   <RTN (Rapid Tissue Necrosis) is more a description of the condition than the name of a specific disease, akin to renal failure as opposed to Polycystic Kidney Disease.  So could it spread?  All depends on the causative agent.  More info here and the related links in blue:  http://www.wetwebmedia.com/corldisfaqs.htm > I have a pink birds nest coral that grew to the point where one of the branches pushed against the rock it was glued to, and dislodged itself while I was on vacation.   <St. Murphy at work again!> I noticed that some of branches tips were starting lose their color so I reattached it, it got worse so I fragged it.   <A reasonable move.> The fragged coral seems to still be turning white from the base upwards on all of the frags, then one of my Montipora cap started to discolor in the middle of the cap about a month ago, and has lost some of the tissue in that area, and has spread to the outer rim. <Sounds like zooxanthellae expulsion, perhaps there is an environmental issue at work here.>      I have gotten back to changing out 10% of my water/wk and running a magnum 250 with carbon.  My water parameters: 150-Gallon Tank Nitrate 0 Phosphate 0 Calcium 400 Alk 10 Temp 77-79 Salinity 1.025 Magnesium 1200 <OK.> Can a build up of salt creep on the top of the tank if dislodged kill corals, or burn them?   <Oh, yes.> I've made corrective action to minimize this just in case. <Good.> I have a couple of soft corals Xenia that's uncontrollable <Heeee!  Often the case!> 7 different types of Acros that are unaffected A couple Milli's (one showing signs that a small area on one branch might be effected. A couple of Red Monti Cap (both are now dying) <Uh oh!> I feed Nori 1-2 times/day for my powder blue tang, and Foxface .  I use Selcon one a week A mixture of frozen Cyclop-eeze, formula 1, formula 2, sweetwater zooplankton, frozen Mysis 2 times/week. Am I missing something that I should be feeding my SPS here? <Seems like a good variety.> I know it's not predatory, and I changed out one of my halide lights because it was over 12 months old. <All sounds good.> Can pruning xenia cause in increase in allelopathy and cause this?   <For the most part, Xenia is one of the least toxic corals, but a few species do produce a chemical that is capable of damaging stony corals.> I have to prune this thing every few days or it'll take over all of the lighting at the top of the tank. <Xenia can be invasive.> Thanks for help, <Welcome!  Mich> -David  

Superglue stops RTN!  - 01/24/06 Hi all, I just wanted to say I have seen this work! It has worked wonders   against RTN for the people that i know who have used it. Just figured it put it   out there so more people would know.    Have a good day and  happy reefing....Lucas (you just cover the affected area with it plus a  little of the good tissue around it. stops it completely and new tissue will grow  over it in time.) <Interesting... to speculate on the action at play here. Bob Fenner, who is reminded of the "Windex scenes" in "My Big Fat Greek Wedding">
Re: Superglue stops RTN!    1/25/06
Hi Bob here's the thread i was looking for......Have a good one and  hopefully this saves some people some headaches! _Reef  Central Online Community - RTN recovery diary of my Solitaryensis tabletop  (pics)_ ( http://www.reefcentral.com/forums/showthread.php?s=&threadid=742509)   <Thank you for the follow-up. Cheers, Bob Fenner>

SPS RTN !!! <?> 8/9/05 Hi Crew, <Ramy> Great site indeed, up-to-date info for sure !! I have purchased an Acropora frag a couple of weeks ago and the base was kind of white, or missing any colouration. <Typical...> After 3 weeks, the size of the white part is still the same, meanwhile, the rest of the frag is very healthy and shows very nice polyp extension. <Good> My question is, is there any chance that this unhealthy part can spread or do you think that it will recover. I have very good lighting, excellent water circulation and all the other corals are doing just fine. Is it true that RTN can spread over a few days and kill the whole piece ? Thank you. <... this whitish area is not likely RTN, but just resultant die-off from the actual fragmentation process... RTN can indeed spread rapidly... I would not worry here. Bob Fenner>

RTN issues 5/4/05 Folks @ WWM, howdy. Recently, I have been experiencing RTN/STN in my tank. It started when I recently hooked up a chiller and tuned it down too low, shocked a couple of things. It went down by 6 degrees overnight from 81 to 75 and probably killed a colony, stressed out 2 other and a bunch of frags died. Over the next few days, the temp slowly came back, so I thought everything should be fine and I started to see other corals bleaching from the base up. This time, I have a salinity problem. I was using a hydrometer with a faulty arm so all the time while I thought I was mixing at 1.025 it was actually 1.021, when I tested it with a new hydrometer <I would really invest in a refractometer if I were in your shoes. They give you very accurate readings and are worth every penny.> ...this is a week after the temp got back to normal and over 3 days the specific gravity was back to 1.025. Anyhow, my question is that does RTN/STN spread and contagious?  < I would not say it is contagious per se.. But if a coral is sitting next to another and dying, it will release toxins which could cause another to recede. So in this case heavy water changes and running fresh carbon would really help get the toxin level down.> Basically most that are affected start to bleach from the base up and few others have patches of white here and there, especially one of my caps. I'm very concerned and don't want this to be an ongoing problem or I will lose the entire tank. I've lost a couple of things and I can deal with that but I have lots more coral too precious to lose...Some affected colonies are permanently attached since they encrusted so they're still in there. I change 15% water every week and it has good flow, O2, water params are fine now. I hope this can be stopped and not sure how I can stop it... < I would really get the carbon going and change that every few days just till things settle down. Also do the water changes about every 3 days just to be sure things are stable. And get a refractometer.. Acros are very sensitive to change so it is important to get that salinity dialed in exact with water changes etc. The only real way to do that is with a ATC Refractometer. Also is it a slow recession? RTN in my experience is almost overnight that you will lose the whole colony. If it is a prize coral that you want to have the best chance at saving, you can frag a small piece of it from a side that is the farthest away from the recession. Hopefully the frag will make it and you will at least have that piece to start a new colony> Please help!!! Thanks in advance... SJ  <Good Luck EricS> 
RTN issues 5/6/05
Anthony, Thanks bro, your words brought some comfort. <Ahhh... good to hear> I'm getting a refractometer now (didn't know about glass hydros tho) so I hope that'll work out. <Ohhh, yes... a good move.> I've also stopped the chiller since there's really no need to chill yet. <Hmmm... your chiller is thermostatic. You should not need to shut this off my friend. Its is a mistake to unplug heaters in the summer, unplug chillers in the winter/cool times, etc... it usually catches folks off guard when the weather changes> Hope that'll help a bit instead of having temp swinging from 79 to 81 and back constantly (AquaMedic chiller - Titan series). <No worries... in this case and most I always recommend an add-on (more precise) (thermostat) controller> I'm starting to think that the chiller is actually causing the major part of the stress... <Indeed... fish pathologists often cite swings as little as 2 degrees as stressful enough to incite a flare-up of parasites, etc.> BTW I do have Eric's book on Aquarium Corals, fantastic book. If I'm in Houston I hope I can look him up and check out his 3-part tank (with mangroves, etc). Anyhow, I met Bob Fenner few months ago at SeaBay meeting and he is a real funny guy... <Very fine folks... they are friends and have my highest regard> ps. Thanks for the tip on trapping fish in reef tanks. I read one of the threads about the plastic bag and live brine and I actually caught my dwarf angel who has been chewing my SPS's...great tip... Thanks again... Steve <Excellent to hear! (the catching part... not the coral nibbling part <G>). Kindly, Anthony> 

RTN? Please take a look at the attached photo (sorry about the quality). Tissue is sloughing off, I assume hermit crab is eating dead tissue and is not the cause. < I would say that as well. > Perused many comments regarding RTN on your site, is this what it looks like? This Acro has been in the tank for 6 months without symptoms and several other Acros look normal. About the only change recently is switch to Reef Crystal from IO. Have not verified all parameters yet, what I do know is pH 8.2, dKH 12, Ca 350, temp stable at 77-78*F. I guess my question is, if I do find something amiss and slowly correct it, what are the prospects for a full recovery? < Looks like a perfect example.  Chance of recovery is very very bad.  I would immediately frag that coral.  I used to advise otherwise but every time I did the reefer would lose their coral.  So now, I say frag many many pieces away from the RTN area and just hope the remaining mother colony makes it.  Sorry I can't be more optimistic but I wouldn't wait this one out. > Regards, George.
<  Blundell  >

RTN in SPS frags I have experienced RTN in a few of my small SPS frags. Where does this come from? It seems to just begin upon the tips of the coral's branches. Should I break off the white parts or just see if it cures itself? Any advise you have would be great. Thanks!! <wow... this is a question that literally cannot be answered in less than pages. RTN is not clearly defined or explained. It is a term applied to several if not many conditions in coral (some pathogenic, some not... rather stress/heat related). Do peruse the WWM archives and beyond for current discussions on this topic. Most of the popular reef authors have written on this topic. Eric Borneman in Reef Corals book is most thorough and current. I discuss it as well in my book on coral propagation. I cannot say much without so much more information (what you call RTN: is it necrotic and rotting tissue or bleaching/expelling zooxanthellae... how old is the coral... did you quarantine it... so much more...?). You best bet is isolation in a QT tank, heavy aeration, ozone would be ideal... but use iodine if no ozone is available. You may also use an antibiotic in the hospital tank as well or in a strong extended bath. Best regards, Anthony>

SPS RTN Event? <<<Anthony Calfo with the follow up>>> Tank Specs: 120G ETS Skimmer 2x175W MH with 2x65W PC ph 8.2 - 8.35, SG 1.025, nitrate 20, calcium 400. <Everything listed seems pretty good. Your nitrates are a little high, but your clam (listed below) will enjoy/consume that. I would like to see you keep track of your alkalinity and temperature.> << Temperature is maintained by a Medusa temperature controller at 80. I have not check alkalinity in awhile - I'm depending on the ESV supplement to keep it in range.>> <<<wow... blind faith. Charming, but not at all safe or recommended <wink>. A fine product but the manufacturer's rec. doses are merely guidelines. You must test and dose accordingly. X teaspoons per X gallons means nothing in a system with 500 clams or 1 clam for that matter. It is the daily demand for Ca/ALK that should determine how much supplement is added>>> I add ESV calcium/alk supplement every other day, iodine every week and coral vital every now and then. I've been moving my tank over from a FO to a reef over the last six months or so. I've replaced the bioballs in the wet-dry and added a bunch of live rock. I've upgraded the lighting as well. I currently have a large Naso tang, a large derasa clam, a couple of cleaner shrimp, misc snails and hermits. A couple of weeks ago I went and picked up a mushroom rock, a zoanthid polyp rock and a SPS - a Montipora. I put the SPS high up on the reef in a place where the return pump created some current. The SPS looked good for two week showing clear signs of growth. Overnight this piece of coral "melted" away. When I got up in the morning about 75% of the coral was gone. <There is an important distinction to be made here. Has the tissue disappeared or has the tissue remain but lost its color?> << The tissue is gone. I have removed the skeleton at this point. >> I did a FW dip (hey, what the hell) knowing it would probably not help. It's been several days now and the coral looks stark white. Any chance of the coral making a recovery? <Again it depends if there is still tissue left.> Is/was this a bacterial problem? <Hard to say at this point.> Any suggestion to how I can prevent/decrease the chances of this happening again? Thanks! <I will refer you to an excellent article by Julian Sprung. It is titled "Coral Bleaching" and it is in the Marine Fish and Reef 2002 Annual magazine. This is a once a year special issue magazine put out by the people who publish Aquarium Fish. See if you cannot find it at your LFS. Hopefully, it will help you diagnose the exact cause for your loss. -Steven Pro> <<<yes... agreed. So many reasons for Coral Bleaching (light/salinity and especially temperature shock <sudden increase of 4 or more degrees), pathogens, weak Ca or Alk levels, etc.>. There just is not enough information to make a fair diagnosis at this point. Best regards, Anthony>>>
SPS RTN Event?
Tank Specs: 120G ETS Skimmer 2x175W MH with 2x65W PC ph 8.2 - 8.35, SG 1.025, nitrate 20, calcium 400. <Everything listed seems pretty good. Your nitrates are a little high, but your clam (listed below) will enjoy/consume that. I would like to see you keep track of your alkalinity and temperature.> I add ESV calcium/alk supplement every other day, iodine every week and coral vital every now and then. I've been moving my tank over from a FO to a reef over the last six months or so. I've replaced the bioballs in the wet-dry and added a bunch of live rock. I've upgraded the lighting as well. I currently have a large Naso tang, a large derasa clam, a couple of cleaner shrimp, misc snails and hermits. A couple of weeks ago I went and picked up a mushroom rock, a zoanthid polyp rock and a SPS - a Montipora. I put the SPS high up on the reef in a place where the return pump created some current. The SPS looked good for two week showing clear signs of growth. Overnight this piece of coral "melted" away. When I got up in the morning about 75% of the coral was gone. <There is an important distinction to be made here. Has the tissue disappear or has the tissue remain but lost its color?> I did a FW dip (hey, what the hell) knowing it would probably not help. It's been several days now and the coral looks stark white. Any chance of the coral making a recovery? <Again it depends if there is still tissue left.> Is/was this a bacterial problem? <Hard to say at this point.> Any suggestion to how I can prevent/decrease the chances of this happening again? Thanks! <I will refer you to an excellent article by Julian Sprung. It is titled "Coral Bleaching" and it is in the Marine Fish and Reef 2002 Annual magazine. This is a once a year special issue magazine put out by the people who publish Aquarium Fish. See if you cannot find it at your LFS. Hopefully, it will help you diagnose the exact cause for your loss. -Steven Pro>

Is This RTN [Rapid Tissue Necrosis]? BOB, <<JasonC here filling while Bob is away diving.>> Need some help having my first encounter with some kind of disease that is attacking one of my SPS corals. One of the lower branches of a tri color coral has lost all of its pigment and has died over night. I have placed the infected coral in its own tank with hopes that the others don't get infected. <<quite wise to isolate it, in case this is a pathogen. RTN isn't really a disease, it's more like a description of conditions - there's going to be something else going on - need to look further.>> The coral that was effected looks like the skin has just vanished with just small traces left on the dead branch. twelve hours have passed and the rest of the colony does not seem to be effected. <<ahh good.>> Any advice how long i should leave it in quarantine? <<perhaps as long as is practical - a month perhaps, two weeks if you can't stand it and it's continuing to do well. Again, if this is a pathogen, you will need time to identify it and treat appropriately.>> Should i do any thing to the main tank? <<run all the normal tests, keep watch in the spot where the coral was placed - in case there is a new predator you didn't know you had, nearby sweeper tentacles, etc.>> should i try to salvage some frags off the unaffected part of the infected colony? <<You could, but if this is a systemic problem with the coral, the resulting frags will take the problem with them.>> Is there a cure or should i let it take its course? <<with the exception of stepping up the observations, wait.>> temp and lighting have been consistent and the effected branch was on the lower part of the colony. <<How low is low? Some/Many of the SPS corals do this to their lower branches as the top branches grow into the nutrient-rich stream/currents.>> It's been 36 hours and the bleaching has not progressed. Am I in the clear, or should I wait longer what do you think? <<I'm a big fan of patience, and because these are all closed systems, you really don't want to introduce [although it may be too late] pathogens. It's a good thing you have the quarantine nearby so you might as well use it for as long as seems useful. Is a difficult question to answer as there's just not a ton of information about the various causes/problems/cures for sick corals - mostly anecdotal, personal accounts. Stay patient, and in the meanwhile you can read through the SPS FAQ's: http://www.wetwebmedia.com/stonyfaq.htm >> thanks Kurt Keener <<You are welcome - I hope it helps. Cheers, J -- >>

RTN Good morning Bob. Have been doing some reading on "RTN". Do you know if there is any on going research on RTN and if they have found exactly what causes it and any new cures or treatment for this ?  <Plenty o' speculation... fungus/es of sorts being carried by the wind... overheated reefs... a combo. of influences...> I have been trying to find some article or on this subject. A lot of the books that I have read don't really say what causes other than maybe stress or changing there environment. <Take a read through "The Modern Coral Reef" books by Fossa and Nilsen, and Eric Borneman's latest (great) tome "Aquarium Corals"... this is an "old complaint" that many thought we were done with (at least in the trade). There is a bunch on this in the scientific literature... I have a piece on how to search this on the WWM site. Bob Fenner> Like more hobbyists I have lost some nice SPS colonies to RTN. Have a great day. Barry

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