So this has been a very busy year where I haven't been able to keep up on my tank as I would like and my girlfriend has really stepped up for me. But last year for no reason I have found at all my fish where dying one at a time about 2 to 3 weeks apart. 7 yellow tangs, rock beauty, all corals, and a purple tang but he died for picking a fight with my blonde naso and losing..... then the shark finished it. The fish just stopped eating and died one at a time. All fish go through QT and treatments for 2 months before moving to the display. I have a B naso, magn. Fox face, and white tail tang along with my shark for over a year now with no loses. I didn't want to keep adding as they died but I am at a loss. Wanting to set up my Qt by the start of the year and try again but I dont want to go through that again. Was hard coming home to remove a dead fish.