NEED HELP!

[Vishaalkumar]

Guys i don't know whats going i have been losing almost one a fish everyday i check everything in my tank and everything is coming back normal my corals seem to being doing fine. my salinity was way too high at 1.028 so i did a water change and not it is at 1.026. my tank temperature seemed to be always at 27 degrees so i set the thermostats to 24 and now the tank with lights on is a at 26. do you think my fish died because of the extra salt or temperature? my yellow tang was healthy and when he died i noticed he had brown under his scales and seemed like he was bleeding from the head? none of my fish are aggressive and all get a long well what could possible wrong?