thank you everybody for the ideas!
I lowered his water, I could see him trying to gasp for air and it was the first time seeing him floating straight! not on his side down on the gravels.

I just check him this morning, he looks a little better! back to his colors, not almost white like past two days.

king2005, even though I change the water weekly, I suspected it must was because of bad water, probably. I should try the bubby wands!

thank you all!! I'm smiling!