I have been outta town for a few days. The house sitter has been watching tank. Naso ate well last night she noticed it dead this am. I attached photo of orange shoulder. Nobody else is showing anything yet but have a gem tang, tusk, Achilles and few gobies. All fish have gone through rigorous quarantine process. Naso was about 4 months and orange has been in for a year. Tank is 1.5 years. All fish have Gone through qt sense start of tank no new additions recently. 320 give to take with sump. Water parameters are on point recent icp test was all normal. I run one every 2-3 months just cause thoughts please.