Stress Lines?

[KrystaK]

I've had Casper, my white Betta for just about two weeks.
I did a substrate change yesterday, I changed from black gravel to river rock and it was all good. I had to take most of the water out as well as casper in order to do this.
He developed very faint red horizontal lines on his body, I've heard these are stress lines. I'm pretty sure the substrate change caused them, now I'm just wondering if there's anything I can do to de-stress him or if I should just leave him be.

Thanks

 

[Liquid skills]

dont put ur hands in the tank it should clear up by its self she should become calmer by her self