First picture: previous tank (half a gallon at most) and yes, that is a decrepit moss ball behind the tank
Second picture: new tank (3-3.5 gallons, can’t remember which)
Things were looking pretty terrible for this poor betta at first, but now he’s swimming around happily and eating, which he wasn’t doing before! It really makes a massive difference to give your fish a suitable tank size and environment. He didn’t have a filter at first either, and it’s a total myth that bettas don’t need filters.
As you can also see, he has fin rot. I’ll have to get a picture of him that’s more recent but he’s already got so much more color than before and his fins have little nubs on the ends where they’re growing back.
A message for everyone: please don’t let your betta fish live in conditions like this first picture! They deserve so much better and it’s terrible for their health. They need space, a heater, a filter, and hiding spaces! I also added live plants, but I think it’s alright to use artificial as long as they’re not pointy or hard enough to hurt the fish’s fins.