Hi, i have an aurtus in 150L tank alone with filteration and WC 30% once a week. water P are 0,0,10

2 days ago he stopped eating. there wasent any change made in the tank and the only other symptoms im aeeing is that he is breathing fast and "puffing" his gills more the usual while breating. I didnt see him or gasping for air.

What do you think is this? what do you reccomend doing?

thank you

heres a vid, today i saw him flashing