Is there a primary cause for RTN in an aquarium?
is a generic term, there are many pathogens that can cause RTN
. This is the reason it is so difficult to treat, it's RTN
, but is it caused by a bacteria that responds to a reefsafe antibiotic? Is it protozoan? Is it viral? Yes and yes and yes, depends on what is destroying your coral.
I wonder why it just affected it and not the other corals?
will only effect stressed, weak or damaged corals. It is contagious and the corals in your tank may be weak enough to succumb so it is wise to remove the coral, but it can be a one coral thing with no spreading.