My Suffering Betta

Question
I have only noticed this yesterday, but my poor four-year-old betta is not his peppy self anymore. All he does is lay on the tank's floor and struggles to get to the top for air. Sometimes he can eat, but I've seen more of his food coming out of his gills and he gives up on trying to eat. He looks horribly skinny, his fins look like they're shredded up, sometimes it looks like he's not even breathing anymore, and he has little black spots all over his fins. Right now my mom and I have put him in his carrier bowel (the little bowels pet stores have the betta in) so he dosn't have to struggle to much for air and food. I was about to flush him today, but when I went online I was hoping that they're is still some luck.
Type:Blue Veiltail Male
Age: Rougly around 4 or 5
Tank: Plants are plastic, aquarium air pump, 1 gal.
Mates: None (but i do have another tank with a girl betta fish next to his and he is able to see her, but does nothing about it, like mating habbits)
Feeding: Once or twice a week, my mother tries to feed them on most days. He has been eating the dried  worm/shrimp pellets(Hikari's baby pellets), but for two weeks we tried this one big pellet(TopFin's 7-day Fish Food Feeders) and the food really damaged thier water so I stopped feeding that to them (I also noticed that he was lieing down on his TopFin food all day but I didn't really think much of it because I thought he liked the food).
Cleaning: Tank cleaning are every four to five months and I do put betta solution to keep thier water clean and safe.

Also, I just find it strange because everything I do to his tank I do to my girl betta's tank as well (e.g. same food, water solution, aquatic plants) and she is perfectly peppy and healthy like the day we got her.

Please help! Thank you!

Answer
Hi JC,
The symptoms you described definitely point towards old age as being your betta's problem here. I must say I am impressed to see a betta live to four/five years old! The majority of bettas kept only live maybe two years--a few reaching three.

Bettas do seem to shrivel up like old flowers whenever they get really old. Its very sad to see them that way but its an unavoidable process. I would make sure he gets enough to eat. The pellet food may be too difficult for him to swallow and chew now. Could you offer him flakes instead? Better yet some frozen bloodworms and brine shrimp.

Maybe try pre-soaking any pellets and slightly crushing them to make it easier for him to eat.

At this point there's not much you can do but continue to keep him comfortable. Being in the little container is a good thing so he doesn't have to struggle far to reach air or food. Just make sure the water temp doesn't get cold.

I'm afraid the little guy doesn't have much longer. But to think he has lived longer than most pet hamsters!

I'm sorry for the bad news but I wish you the best!
Karen~