My betta fish Comet developed a large tumor on his face, causing his mouth to become disfigured and hindering his eating abilities. Sadly, he passed away. Shortly afterwards his former mate, Cupid, began refusing food and becoming extremely lethargic. They will both be severely missed.

Oh no RIP Comet and Cupid.

Thank you all for your condolances. At least they will swim together in the big sky-pond.  

I think the tumor was old age. In my experiences with bettas, when they reach a certain age their health starts to rapidly decline. They stop eating and blow bubbles through their gills. Before Cupid died she had a seisure of some kind. She began to writhe slowly, touching her nose to her tail. She would stop breathing. Then she would recover and act like nothing happened. It was so hard to watch, she looked to be in great pain. Now she is in a pain-free place. <3

Rather like Romeo and Juliet, no? 

I do miss them though. 

Thank you, goldfishluver.  I have seen many a fish pass away while I was still learning about how to take care of them. It's always hard to see their health deteriorate until you just can't watch anymore and are forced to humanely put them down. I hope when we die we can see them again. To say hello to all our beloved pets would be a wonderful experience, and also a comforting thought.