Yes there looks like something else is going on and we are now treating the symptoms of some kind of underlying ailment.. anything else you notice before this happened? did his stool change at all, or any flashing before the rot, or anything else change in his behavior? Fin rot is usually a symptom of something else if your water conditions are kept at good levels, as a healthy Betta in clean water fights it off on his own or would never get it...Demeter said:
Sometimes he does dart around and then he swims into the pots that is in his tank I don't see any worms and he likes to float at the top close to the heater and I haven't added anything new to his tank except I replaced his heater.Warren Tyler said:Look really close at the anus , you see any clear worm like or stringy ? If its there it is hard to see.. Dose he have any trouble getting to the top or bottom of the tank when he swims? No darting around the tank? You will need to treat the fin rot regardless as he is not able to, but we will still need to find out why he can't fight this off, it could be an internal parasite/bacteria infection compromising his immune system... Any additions to the tank lately? any big changes to the tank??