Don’t understand what is going on with my tank, I’ve had a sailfin tang for about two months and it has been doing great. Last week I decided to buy a blue hippo tang and it was doing fine , Two nights ago I found my sailfin dead checked all my water levels and everything was up to par, then last night I noticed my blue tang was laying on its side which I know sometimes they do this when they are stressed but then this morning I found him completely dead also... just don’t understand what’s going on I also have two clowns and one damsel and a goby in a 60 gallon tank.... tank has been running for a little bit over nine months and have not had anything die until I started with the tangs