My yellow tang developed whatever this is almost overnight. Woke up to it laying on the bottom and died shortly after. Anyone know what the disease that caused this is? And if i have to quarantine my other fish now. My water parameters are all optimal i test every single day.
sorry for the loss. Can you provide some more info about your tank and livestock. how long its been up, how long you had the yellow tang and have they been through qt before going into your display?
From the picture and the marks on the YT my guess would be a bacterial infection. That fish also looks a little on the skinny side to me.