Hello, everyone.
The attached movie shows the fish in question.
The tetra seems to start losing balance since yesterday.
None of the other fish in the tank has any signs of sickness. Water quality is fine, with 0 ammonia and no2, and ~20 no3.
This tank has been established for more than a year now, and this group of emperor tetra was in the tank since the start. This is not the first emperor tetra to have this sickness. In the past, there was a couple of emperor tetra with the same sickness. All of them are female, and only one fish will show signs of sickness every time. This only happens every few months. I thought it was only particularly weak individuals, but this seems to keep coming back.
As I understand, this is probably some sort of fish bladder sickness. What I do not understand is the cause and how to prevent this from happening again. Anyone can share some insight on this?
Thanks in advance.