well, it's not exactly crashing as all my corals are doing well but my fishes are different story. i have 2 oce clown, tail spot blenny, yellow coris wrasse, hector goby, and a diamond spot goby in my tank for the longest time. they all went through the QT process and have been thriving in my display tank until two weeks ago.
first it was my hector goby. it mysteriously disappeared two weeks ago and only to found out its upper body floating in the water column. then this past Monday, it was my tail spot gone MIA. i looked everywhere and it could not be located. i did find fleshy remains of "something", which i suspect is the carcass of the blenny. Tuesday night the diamond goby went berserk and tried to jump out of my tank. i thought it was just a normal fish trying to "carpet surf" phenomenon. Wednesday morning, i found it dead among my corals. Thursday, my clowns have spots on them(ich maybe?) and the yellow coris that usually hangs out during the day was hiding in the sand bed, which is odd since he never did that during the day. i immediately scooped them out and put them in my QT tank and start the meds.
my nems, cleaner shrimp, 2 pom pom crabs, and other inverts are unaffected.
tank size: 29gal
skimmer: Reef Octopus BH1000
parameters: ph7.8, ammonia/nitrate/nitrite =~0, phosphate = somewhere between 0 and 0.25
powerhead = 2koralia totaling 3X tank volume
30% water change on Tuesday and another 30% water change scheduled for today after work.
I guess my question is: can the fish get sick/ich if the corals/inverts are fine?