Current RTN theories

[Chuck Anderson]

Hello,

I was wondering what the current theories are for the causes of RTN (Rapid Tissue Narcosis)?

[tubs]

As far as I know there are two "schools" to this. One is that it is based on a protozoan or bacterial infection caused by primary stressors and the other states that there is no proof of a significant amount of bacteria or protozoan and go on to say that RTN simply is a response to environmental stressors. Environmental stressors could be chemical warfare between corals, and chemical and lighting changes for instance.

So I don't know for sure. I recently went through a crisis like this and was caused by making too many changes in my tank all at once. I was finally able to subdue the spreading by doing a large water change and putting in a large amount of fresh GAC. The catalyst to my experience was a lighting change and a large colony of cladiella wasted away really fast and my mistake was to not do a water change as the cladiella could have released a significant amount of toxins into the water. At the same time the other corals also started showing signs of bleaching due to the lighting change. This was my other mistake assuming that a bulb change would not be signficant and despite knowing better I became careless and didn't shorten the photoperiod.

Before I could take appropriate actions I had already lost a couple of colonies and some frags. You just feel helpless to see the tissue flaking away from long time resident SPS colonies. Even fragging didn't work.

So in my case I believe RTN was caused by environmental stressors. Hypothetically, the weakend corals could succumb easily to secondary infections, which is usually the case for any weak animal that diseases can more easily take root.

Borneman states that studies have not revealed significant amounts of any bacteria or protozoa on affected RTN tissue and describes RTN as sort of a shutdown reaction due to environmental stressors. Personally I'd like to see more scientific studies on RTN tissue to validate that Borneman's claims. If you're interested in more of his writings on the subject, get his new book "Aquarium Corals".