Your tank is on cruise control and all SPS corals are in a happy zone, growing and thriving like you had always imagined. Then one day the lights come on and your eyes zero in on a dead coral. What the heck? How could that happen when everything was going so well?

 

Reef keeping can be a humbling experience, trying the patience of both beginners and veterans. Sometimes bad things happen due to poor husbandry and other times there is no clear explanation. I can sleep better at night when something bad happens as long as I know what caused the problem, allowing me to prevent it from reoccurring. That’s just the way I am wired. I like closure. It’s those mystery events that drive me batty.

 

Rapid Tissue Necrosis or RTN can be one of those mysterious events. RTN is when a SPS coral suddenly loses tissue and turns white. This bleaching event occurs within 24 hours and can effect the entire coral or just a part of it.


Why RTN Happens?

Let’s first focus on some of the logical reasons why RTN might occur. One has to do with stability. SPS will become cranky and stress out if certain parameters such as alkalinity, calcium, pH, salinity or temperature swing significantly up or down. The wild swings will put corals in a weakened state and make them more prone to some sort of infection. Laziness is not a reef keeper’s friend so it is very important to be diligent and test key parameters on a regular basis. One should also make sure test kits are accurate and not generating false readings.

 

Stray voltage from a power head or some other piece of equipment is another possible culprit as are pests such as Acro Eating Flatworms (AEFW). RTN can also happen when granular feric oxide (GFO) is overdosed, something I experienced with a former tank.

 

Ok, now let’s address the mystery surrounding RTN. Sometimes there is no obvious reason why it occurs. Some believe a mystery case of RTN is due to some sort of killer bacteria or virus introduced with a new coral. Preventative dips and, ideally, a quarantine system will help the most on this front.

 


 

I recently experienced RTN with an established frag and ruled out all of the likely culprits. Was it due to some “bad” bacteria? Who knows. Did I lose a little sleep wondering whether it would spread to other corals, a nightmare scenario? You bet. It’s the unknown that keeps me awake at night when it comes to my reef.

 

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If you are looking for additional insights and information, please explore my many other reef tank and SPS related articles as well as my book, A ReefBum’s Guide To Keeping an SPS Reef Tank: A Blueprint For Success. Additionally, you can see all of my reef tank videos online now as well as my Live HD Webcam.

 

Happy reef keeping!