Clowns moving sand

[dieselkeeper]

I have 2 Clarki clownfish with a haddoni nem in a 40 brdr. The clownfish keep moving sand with their tails until there is a good size depression is in the sand. So I removed the nem and the fish still moved the sand. So I then put some large rocks in the depression or hole. Now they are still moving sand behind the rock, in front of the rock. Why?

 

[Tahoe61]

Because that is simply what they do. They might be cleaning before a spawn, but that is typical behavior for most clowns.

 

[Tori]

My clown looks me in the eyes and does it whenever I come up to the tank. I assumed it was some kind of a threat or the clown equivalent of the middle finger...