Possible sick fish, please help!

[Sonny bats]

I've noticed my one clownfish has lost some of his color on his back, the black has faded to a lighter color. And he has been swimming sideways for the past few weeks, I know clownfish are really weird and didn't think anything of it, but something doesn't look right.
His gills look like they are moving a lot more then they should and his mouth continues to stay open. Meanwhile my other clown is perfectly fine,









Could it be Marine ich?

 

[Sonny bats]

Goin to test water parameters to see if anything Is off, just did a water change a few days ago tho.