rapid tissue?

[Freckles]

What are the signs of rapid tissue recession?
I lost my bubble coral last weekend Now, my green open brain only has a small piece of tissue on him I dont understand what is going on? It keeps getting sand kicked on him too ...... Would it help to move him to the back of the tank of the top of the tank so he can possibly recover?

[dark horge]

Sorry to hear that, Freckles


RTN, or rapid tissue necrosis, is precisely that --rapid rot and disappearance of live tissue that CANNOT be attributed to any of the known coral diseases

RTN is a convenient term for a phenomenon that may turn out to be one, four or twenty different diseases (aside from all the band diseases, SDR, etc.) No one knows yet what causes this apparent disease, but we know it isn't bacterial in nature.

It has been anecdotally linked to the introduction of a new coral to the system, and to temperature change. My personal belief is that it is a faulty (due to malnutrition) internal reponse to perceived general attack from without.

So far, the appropriate response to apparent, so-called "RTN" has been isolation of corals and generous water changes ---whatever the trigger or pathogen, water changes will dilute its presence.



Good luck.




FWIW, a healthy 'brain' coral can clear itself of reasonable amounts of sand. But this does require energy, and on the off chance that your corals are low on reserves, elevating the coral is a good thing to try.

[Freckles]

Thank you, I will move it up higher. Is there anything else I can do for the brain? He had such a nice bright green color. I hope nothing happens to my frogspawn .........

[reefguy]

rapid tissue necrosis (death) can happen for many reasons, but i have seen a few patterns in the past.

first, rtn can occur because of a bacterial infection or an attack by a neighboring coral. one of the first things to do is treat the coral with iodine (to prevent further infection) either by dipping or localized treatment with a syringe.

the next is, obviously, to move the coral itself.

also, rapid tissue recession can be caused by inadequate lighting or by poor water quality. check both...

finally, thoroughly check out your LFS. maybe they are selling you unhealthy specimens...

hth..
keitho

[reefguy]

and, btw, the other thing i have learned...if your coral is TRULY healthy at the onset of such conditions, it will pull through with little or no problems

[dark horge]

Originally posted by reefguy
...rtn can occur because of a bacterial infection...
keitho

Hello

Borneman & Lowrie bravely tried vectoring for a bacterial causative agent and came up nada.
That was back in 1998 and it still stands.

Here's a transcript of an online discussion from their viewpoint:
Borneman & Lowrie 1998

Again, I believe so-called "RTN" is possibly a result of faulty autoimmune (or general defense) response on the part of the coral ---which in turn I suspect has (mal)nutritional roots. You are also probably thinking of other diseases when speaking of a 'coral pulling through'. The operative word in so-called "RTN" is 'rapid'. I have not heard of any meaningful number of cases where a coral recovered from "RTN" without hobbyist intervention.


----------
Just to be clear:
RTN has yet to be properly characterized in a way that would accord it even informal status as a disease, outside of this informal little hobby of ours. There are 6 accepted coral diseases that I know of:

Brown Jelly Disease, a rather descriptive hobbyist term for a condition attributed to protozoan infestation, affecting a broad range of corals.

Black Band Disease, attributed to bacterial pathogens (Beggiatoa spp., and sulfur reducers like Desulfovibrio spp. )in concert with cyanobacteria (notably Phormidium corallyticum), the latter producing the 'black' band on many massive corals.

Aspergillosis, attributed to the fungus Aspergillus sydowi, affecting many coral species.

White Band Disease Type II, affecting Acropora, and authored by abiotic stress, paticularly temperature change. Note that Type I WBD does not feature the advancing band of bleached live tissue, ahead of the 'death' front.

Plague Type II, which affects 17 species of coral, and is attributed to the bacteria Aurantimonas coralicida (I think this is what is most often confused as RTN in this hobby).

White Pox, attributed to the enterobacteria Serratia marcescens


As for the other oft-bandied-about coral diseases...like
White Band Disease Type I,
Yellow Band Disease/ Yellow Blotch Disease
Brown Band Disease,
Red Band Disease,
Yellow Line Disease,
Rapid Wasting Disease,
White Plague Type I,
Patchy Necrosis,
Stress Related Necrosis,
Shut Down Reaction,
let's say there looks to be distinctive smoke, but they've yet to find the fire.
As far as RTN is concerned, even the smoke is not sufficiently characterized.


I truly HATE skimming through such an involved topic, just for the sake of brevity, but... I think this calls for a brief collation of known coral diseases, symptoms and pathogens.

Unless Chris wants to do it (speak up, man!), I might post it as a separate thread over the weekend.