Heís been ok the past couple of days but today, heís staying at the filter, breathing by surface. Looking a little strange. He didnít reach for food floating at surface. I got him to move a bit. He looked like he was struggling to swim and went back to the corner of the tank by filter and even went sideways a little on the way there.
Tested water. All levels ok (pH = 8.0, NH3
/NH4 = 0, NO2
= 0, NO3
I added fishkeeper and turned on airstone.
What is going on and what can I do?