Well, the reason i know its not a bacterial infection, but more of a water issue..is..wild colonies tend to RTN/STN more in percentage than aquacultured pieces. The odds of a wild colony to perish overnight due to RTN are bigger than the chances of that happening to an aquacultured colony/frag. Its just light wild caught fish and captive bred fish..Aquacultured are much more resistant to rough water parameters. So, best advice i can give..keep your water quality high, Ca. and alk. in check (or as perfect as possible) READ THE REQUIREMENTS for each coral (which ones like high flow, low flow..higher light..lower light)..not all corals are the same.."One of my 2 acros died!!."..maybe because each one has different needs..so, if you give them what they need, no STN/RTN for you..