Sick Acara breathing heavy

[Olsonshereen]

My electric blue acara has been not eating for days and heavily breathing. I have oxygen added to tank and all other fish seem fine. I woke up this morning to having my acara I have had for years dead. Could this have been a parasite? He’s gills looked fine just seemed to be darker past few days just seemed to not been eating and breathing very heavy.all thoughts welcome please!!

 

[Aiken Drum]

Could you give as much information as you can from the "unhealthy fish" sticky please.

https://www.aquariumadvice.com/forums/f17/before-posting-about-unhealthy-fish-read-this-32451.html

How old is the fish? Could it be old age?