I have had a fair bit of luck keeping a variety of fish however the melanurus wrasse I just can not seem to keep alive. I have tried 4 times now and each one has died either in quarantine or in the display tank. My latest casualty, however appeared fine in the qt tank and alright the first day in the display but after that I saw him with this white what looked like maybe a burn on his side. I have 2 clowns, mandarin goby, diamond goby, and a anathis all of which are/have been healthy for 3 years. I have a 75 gallon reef with a sandbed. I am wondering if anyone could shed some light on what could have possibly happened.