Hello! I had bought a Mural goby 3 days ago. The first day it was fine. It was sifting sand and even made a couple homes. The second day it went missing. I come home today and found it dead. The tank is three years old. It was converted to a reef tank 7 months ago. Other fish are convict tang, melanurus, tailspot, cleaner shrimp, and cuc. Any idea what could have happened? I didn’t see any signs of ich or flukes.