Sadness at the office

It looks like my little betta buddy at work (Dr. House, lol) is dying. I'd posted previously about him having fin rot and apparently beating it but taking a long time to grow his fins back. Unfortunately, his color has been steadily fading for the last few months, and he has been very lethargic as well. I got to thinking that he is probably fairly old as I've had him for at least 8 months and he was fully grown at the lfs. So, he's probably at least 2 years old. Not all that old, but with the stress from the fin rot, it's probably doing him in.

I really noticed the lethargy on Monday when I came in to work. He struggled to stay at the top to eat his FD bloodworms and left most floating when he normally gobbles them right down. Attacks them, really. Tuesday I have him fd baby shrimp, but he didn't even see them. Of all his foods, this is his least favorite, so I have a couple pellets since he wasn't eating any of the shrimp. I didn't see if he grabbed any. Yesterday I gave pellets since I figured those are the easiest for him to grab. Today he got the same. I haven't actually seen him eat since Monday, though he does swim up to the surface at least. But he struggles to stay up like he doesn't have the energy.

Also, I've noticed bubbles coming out of his gills after he rises to the surface to breath and then comes down. Thought that was weird and wrong.

I can't think of anything other than old age to explain his trouble. I did add some anubias to his tank last week that had been left in the freezing weather at least overnight, and those did die. They were in the tank a few days, but I'm not sure if this has anything to do with it since the symptoms having been there longer. I did do about an 80-90% wc Monday as well.

I feel so sorry for him since he looks so miserable. He mainly just sits on the bottom and barely moves. He doesn't own the tank like he used to.

It's a 2.5 gallon bowfront (the kit at Walmart). I have a sponge filter in there now. Originally, I had the Whisper intank filter that came in the kit until I realized that it was ripping up his fins (contributing to the fin rot). The heater is a 7.5 w Jr. Aquatics submersible. That plus gravel is all that is in the tank now since the plastic plants were also (I think) ripping the fins. I haven't found suitable decor that I like yet and was planning on adding live plants like Java fern or anubias.

He actually looks slightly better today, but only slightly. I'm reluctant to lower the water level because the sponge filter output will be much higher than the water level. I read about cutting the tube to make it shorter, but I haven't done that yet. I don't want to cut myself or cut the tube crooked. It's this Hagen sponge filter.

Oh, I don't think I said when I do wc's. I do at least a 50%, usually more like 75% water change every week but have been meaning to do them more often. I'm considering taking the tank home so that I can keep a closer eye on things and do water changes more often without interrupting everyone at work. I share an office with several people.

The temp is at 80 degrees but occasionally rises to 82. That's partly why I want to bring him home because the temp in the building isn't always consistent. They turn down the heat in winter and the AC in summer, so I think on weekends it messes with the temp.