My diamond goby moves sand constantly. He settled down to having a favorite place to pile the sand and I knock down his pile every few days just so he has something to do.
He sifts sand everywhere though and it is an obsession. Obviously, I don't put corals in his favorite area. He loves to collect his little trinkets from around the tank and take them to his favorite pile.
He is very social and is the first fish to go investigate what is happening.
If a fish gets huffy with him, he will spit sand on that huffy fish!
One day I had a fish die (sad- he jumped out of the tank and although I got him back in and he survived for many hours he eventually died) and his body slid clear into a cave where it was going to be very hard to retrieve the body without moving pounds of live rock. As the tears were flowing down my face over the demise of my favorite fish, Curmudgeon went and picked up the body and carried it to his little treasure pile. I had to laugh in spite of my sorrow. He didn't even get offended when I gently removed the body.
You'll enjoy your diamond goby once you get used to his sand sifting ways.