I purchased 3 newborn burrfish 10 days ago. When I brought them home I preventively started treated them ich-x. On the 3rd day one of them stoped eating and then ended up dying the next day. He had a few spots and was heavy breathing. I decided the Ich-x wasn’t working the night he stopped eating and had some spots. I then did a large water change and started the transition to hyposalinity. The other 2 fish have been fine since. They both have an appetite and seem to be acting normal. But I noticed they look sort of dusty. Is this something to be concerned about? I am doing daily water changes at 50%. I am also treating them with stress coat when doing the water changes. The ph is also normal. The pictures where the fish is skinny is when I first got her the other 2 are from today.