A clownfish question

[Jedi knight]

I have 2 clownfish in my tank both are doing great eating well but one of them keeps rubbing his body on the sand bed when I look at him there is no ich or parasites either it’s grown quite a bit since I’ve had it. Anyone know why my clownfish is doing this

 

[James M]

Is it doing that in a corner of the tank ?

 

[Jedi knight]

Yeah behind the rocks does every so often

 

[Jedi knight]

Is it doing that in a corner of the tank ?

Yeah behind the rocks every so often

 

[James M]

Any pics of the clown ?