So this will be an unreasonably long post but the crux of it is I have 2 tanks, a 30 and a 66, both are covered so theoretically these guys couldn't jump out. I started with the 30 but upgraded to a 66. I kept 2 Clowns in the 30 and added a Valenti Puffer to that tank because my daughter loves them. I moved everyone else out of the 30 to the 66 including the cup so the puffer didn't make a meal. I added a orange banded prawn goby to that tank to keep the sand clean with the cuc gone. I put him in, saw him hanging out on the bottom day one and haven't seen him in 2 weeks. Haven't found him on the floor and haven't seen any burrows or shifting sand. In the 66 I had a diamond goby that was always out and about and active all day. A week ago I added a Short Tail Tang and haven't seen the diamond since and have noticed my firefish in his burrow. I haven't seen any new mounds or shifting sand in that tank either. I know these guys can be reclusive but I haven't seen any sign of them and am not sure what happened. I really enjoyed the diamond. The banded I never even got to know. Any thoughts? I've considered replacing both but don't want to create an issue if they aren't in fact gone.