I'm guessing my former tank (29g, and too small) was about 5 or 6 months old when I bought a small diamond goby. It had been trained to eat offered foods by the LFS, and survived drop-acclimation (being spilled out of bag onto carpet, and then tossed into tank when I panicked).
My sand bed was maybe 4 inches deep in one corner of the tank. Once the goby recovered from the shock of its unorthodox introduction into the tank, it went to town! That little fish tunneled everywhere under my rock, and endured constant harassment from my flame angel. The tank was a veritable blizzard of sediment for a couple weeks, and my rock was coated with sediment up high, and sand down low. Finally things settled down - I cleaned up the rocks, the sandbed was clean, the flame angel had died and life was good for the goby. Very entertaining little fish, and he ate the mysis and meaty pellets I offered readily.
Then I had to break down the tank for a move, and I gave the goby to a friend of mine. He already had a diamond goby in his 55g tank, but it was a much larger specimen. The larger diamond goby immediately chased mine all over the tank until it died.
I hope that helps you some while you research this fish!