Unexpected death

My Pakistan butterfly died overnight. No sign of anything wrong with him at all.

Since I did a 20% water change a couple of days ago due to a nitrate reading of about 20 could the death be because of the nitrates or the water change.

Really hard to stomach this one since all the other fish look and act quite healthy.

What a bummer, kind of ruined my day.

Besides the routine checks of pH, ammonia, nitrite and nitrate what else should I be testing for?

Any help would be really appreciated.

Thanks.

 

Sometimes they are also stressed to the point of death. Someone spooked him maybe?

 

Sorry for the loss.

 

I lost 2 perculas in the last 24 hours, sigh. Sorry to hear about your trouble. There must be somethign in the air, or the water rather.

 

well did you have your salinity exactly and heated to the same temp? also your nitrates may have been to high how often do you test and how often are you adding fish normally what i do is add a small fish i have in my qt tank to keep it cycled and move him in there then when i get a new fish its already partly cycled for that next fish