so i have a 75 gallon tank fish, 1 anmone with like rock. every time i add a new fish to the tank it seems to get ich. i resoved 3 times now . so 2 weeks ago when i went and got a regal tang i decided to put it in a qt tank did fine no sine of ich still treated for it but none . i put it in my display and now it has ich. so my question is does my system have ich or do the fish have ich im not seeing at first. and if the system has it y dont the other fish get it.