So I have a diamond goby....or HAD a diamond goby. After QT, I put him in our 100 gallon AIO DT in mid September and for the first 48 hours he was around. I literally have not seen him since so I assumed that he died (no idea why). Every day since he went missing I look for him hoping he's there somewhere...I have checked the overflow (nothing there) and I have looked around on the floor even though we have covers (but they aren't super tight)...NOTHING. A few week ago, we went on vacation for about 12 days and I came back to a large section in the front of my tank where the sand (2" deep) had been cleared away and there was a bare bottom. I was super excited....I covered the spot up with sand and then a few days later another large bare patch appeared in the back of the tank. I covered that up with sand and we were away for the weekend and another bare spot appeared in the back. It's not the wavemakers...they are pointed up to the surface so it had to be my diamond goby....right? I only have 4 fish....flame angel, foxface, cardinalfish and a lemon damsel...a few TINY hermit crabs and some snails. I look for him constantly and have never seen him. He never comes out when I feed the others their mysis or brine shrimp. Is there a particular time when goby's are out and about? And if he is actually alive, will he get comfortable enough to come out so I can actually see him?