Hi I added a diamond watchman goby 25 days ago in my 54 gallon corner tank. He was drip acclimated and I have never seen him since he was added to the tank is it possible he burrowed and just died under the sand somewhere? He has no aggressive tank mates and my readings for Ammonia and Nitrite have been 0 consistently and my nitrate is usually in range from 0-10PPM I tested a couple days ago and my nitrate is around 40 Ppm so i did a 10% water change and tested a few hours later and nitrates are at 40 PPm. The next day I performed a 10% water Change waited a few hours and still at 40 ppm so I change 20% of the water and wait a few hours and still at 40 ppm later that night. Today I test again it's 40 ppm Nitrates, ammonia and nitrites are reading zero and Ph 8.2 salinity 1.024 read with a Refractomer, Should I go looking for the suspected dead diamond goby? He was 4 inches long. I have 77 pounds of live rock in this tank and 80 pounds of livesand, and would it be better to let the clean up crew maybe get him or go searching for a body which would cause stress to the other inhabitants plus the risk of crushing one of the cleaner shrimps in my tank and smaller fish. Any feedback would be great thank you.