Rapid Tissue Necrosis (RTN)

[ldrhawke]

Waking up to see my SPS being attacked with a case of RTN is not a good way to start the day. My SPS have been doing great for the last 6 months have had great growth. I was starting to believe I beginning to have a handle on how to keep SPS. 6 months ago I had gone BB and completely redone my tank to get good flow. In the morning my orange M. capricornis had a small spot of heavy white bacteria slime, under which the coral had bleached white. Having lost a number of SPS to RTN earlier I was concerned. When I got home that evening the small white spot was now ½ the capriconis and a couple of other very nice acros showed signs of RTN. WHY? All the water parameters were good and I hadn’t had any sudden temperature changes,

I’ve tried to figure out what happened to cause and if there was way to stop it. I just finished reading Eric's thoughts on the cause and affect of RTN in his article: http://reefkeeping.com/issues/2002-03/eb/index.htm and I fully conquer, with his comments about stress and bacteria infection.

The first thing I noticed a couple of days ago was the SPS were not extending polyps as normal and they showed signs of stress. I started reviewing what I might have done to possibly cause the problem. Then I remembered, about 4 days ago I rearranged and removed some live rock. When moving the live rock I found several large blooms of orange colored sponge between the live rock which were torn apart in the process of moving it. It was like the rock was covered in wet bread in the areas that the light didn’t reach. I cleaned the sponge off the rock but I didn’t spend a lot of time doing it. I have never had heavy sponge growth like that. I am guessing it may have occurred from my dosing iodine for the last month. From what I have read sponge is often heavy in iodine content and they release a lot to toxins when they die. Moving the rock around might have triggered that toxic release and a result stress on the SPS. That stress probably made the SPS very receptive to bacteria infection. The way the RTN has rapidly spread from the white slime, I have no doubt it is contagious and bacteria in nature.

I immediately did A 30% water change. It was apparent by the third day the RTN was still moving quickly. One of my acros had lost ½ it colored tissue from the bottom up and the white remaining structure was now also showing spots of red cyno. It was apparent I was on the verge of losing a lot of nice SPS. As a last resort I figured if it was bacteria in nature maybe using Ultra Redslime Remover could help because cyno is bacteria and it brings it under control. It has now been 48 hours after dosing and it has at least slowed down the spreading of RTN.

I did another 30% water change this morning and some of the SPS are again beginning to extend. I will do another 30% water change tomorrow and I’m considering a second dose of Redslime remover. At this point I don’t know if the RTN is under control or if Redslime remover help to kill the bacteria. I’ll keep everyone updated.

It is sure a wake up call to the toxic nature of death, especally of a sponge and a lot of other soft corals, and the stress related danger of keeping them in the same tank as SPS.

[Reefland]

Wow that really stinks, but I feel your pain as we have been there too. I have found it best to take the loss and immediately break out the fragging shears when any RTN starts. It's painful, especially when your hopeful that it will stop and you can save most of the coral. Unfortunately, it's more often than not that the entire coral will die. Fragging well above any tissue recession and disposing of the coral that has RTN'ed is a better option and at least, in most cases, you can save a frag or two that can regrow into the colony you once had.

[saltjunkie]

i just lost a closed brain to RTN.. i have only had it once... year or so ago...
my prized candy lost a bunch of heads, i fraged it all up... now i have 2 main colonies,, i saved some of it that way..
But this closed brain i had, i have had for 5 or so years.. the coral is actually shaped like a human brain, with the lil brain stem and all.. it got Rtn on the back.. just a lil spot... 2 days later in my sump the skeleton is just there,, and it took out one of my sps frags too..
in my case.. nothing in the tank had changed.. water, temp, tankmates.. arrangements, etc..
I feel that Rtn is just something that happens.. like a cold.. to us..

but hey i am very simplistic when it comes to reefs.. so my opinion may be way off base..

[zhenya]

Hi John,


Interesting observation on the use of antibiotic, however, it is probably impossible to tell exactly what type of malady affected your coral. I'm pretty sure the use of antibiotic took care of bacteria and your rapid water changes probably helped the most in terms of getting whatever toxins were present in the water after the sponges death.

On a side note, while browsing your website I couldn't help but notice that you have a wrasse that you have named "clown wrasse". Do you still have it?
I hope you realize that this particular wrasses( Coris aygula) get as large as 120cm in Nature.
http://www.fishbase.org/Summary/spec...iesname=aygula
I used to have one, juvenile like yours, bought it about 7 years ago only to trade it to the LFS three years later. It became very agressive and went after my clams when it reached about 5-5.5 inches in length and you can forget about keeping shrimp.
Just figured I'd let you know if you didn't know it already.

[ldrhawke]

Hi John,


Interesting observation on the use of antibiotic, however, it is probably impossible to tell exactly what type of malady affected your coral. I'm pretty sure the use of antibiotic took care of bacteria and your rapid water changes probably helped the most in terms of getting whatever toxins were present in the water after the sponges death.

On a side note, while browsing your website I couldn't help but notice that you have a wrasse that you have named "clown wrasse". Do you still have it?
I hope you realize that this particular wrasses( Coris aygula) get as large as 120cm in Nature.
http://www.fishbase.org/Summary/spec...iesname=aygula
I used to have one, juvenile like yours, bought it about 7 years ago only to trade it to the LFS three years later. It became very agressive and went after my clams when it reached about 5-5.5 inches in length and you can forget about keeping shrimp.
Just figured I'd let you know if you didn't know it already.

I know about the Coris aygula, but not until after I bought it. I will get rid of it before it can't turn around in the tank. It is an aggressive little bugger. Loves to tear up my crabs...even the large Sally Lightfoot. A lesson hard learned....I need to set a trap for it and get it back to the LFS. Pretty fish other than that.

The coral are looking and responding better, but still a lot of RTN damage to the sps. I hope the RTN is in check. I'll have a better idea over the next week. If I ever notice it happening again, I will immediately dose the antibiotics and start water changes. Right now, it looks like the RTN would have done a lot less damage if I didn't wait a few days to start treatment.

Most of the damage causing bacteria is just sitting in our tanks....just waiting for opportune conditions to seize the day from a weakened coral or fish.

From now on I will start doing 25% weekly water changes. I was doing it every three or four weeks. I believe it is the cheapest, easiest, fastest, and most positive way of keeping all aspects of maintaining water quality for SPS........from pH to Ca and ALK, and controlling toxic build up. With weekly water changes the tank is less apt to slowy deplete or allow the essential chemicals to get too far out of balance. I use Reef Crystal salt and it has extra essentials, including Ca. That is 10 -15 gallon water changes from a drum of salt, which is about $3.00 a change. Personally, I think it is as cheap as adding addtives to keep things in balance, which are easy to screw up and cause more damage than good.

The problem is the coral can slowly acclimate to even poor water conditions and then a large water change with good quality water can end up being almost as bad a shock to the coral as what you are trying to correct.

Sorry about the continuous editing...just got by iPod Nano delivered and playing with it, and charging-loading songs on it while I type. Damn it is small and neat.

[ldrhawke]

Update.......the coral still appear under some stress, but the antibiotic does appear to have stopped the spread of RTN.

As I stated earlier, the RTN was rapidly creeping through my acros, like Grant thu Richmond, and the tissue was virtually falling off as I watched. At this point the spreading of RTN appears to have stopped completely. The lower sections of several of my nice acros is down to the white calcium bone and is now starting to darken a little with slight traces of algae. The colored sections remaining near the tips are again starting to extend polyups and appear more normal.

The Redslime Remover antibiotic has without question helped to bring the spread of RTN under control. Only time will see if it is permanent, or if it starts up again. All that remains on several acros is the upper portion colored tips. The remaining tips have started to look normal. If they do start to regrow, I'll try cutting off a few tips and glue them into the naked lower sections to fill the void.

The Redslime has not had a negative response on any other coral or fish that I can see. I have cut way back on feeding, to a single reduced feeding everyother day. I figure the antibiotics might have killed a lot of the good nitrifying bacteria population and they are longer available in quantity to digest the fish and coral waste. I believe all antibiotics should only be used as a last resort on people or acros, otherwise you risk their having no affect when they are really needed.