My betta was a very dull blackish blue color to begin with. Almost grey in some lights. I have him in a 3 gallon tank by himself right now with a heater and a Tetra Whisper 2-10i filter. The current was a bit much for him so I kinked the line on the filter to about half power. He has 2 big fake plants in the middle and do not seem to have any sharp ends for him to snag his tail on. I also put some aquarium salt is his tank last week and do 25-40% water changes weekly.
Now my question involves his tail. It seems to be very thin now and tattered on the ends. I can't tell if it's old age, or fin rot. Or, if he had fin rot when I first got him and his tail grew back a little because as you can see in the older pic his fins were tattered in a different way. He also has black spots going up his fins that I don't recall being there before, but I saw a similar post on this forum with a betta that had the same kind of dots and everyone believed it was just the betta's natural colors/patterns.
The pic on the left is of him when I got him three months ago. Then one on the right I just took. It's hard to get a good pic of him because he darts around when I get close to the tank. I'll try to get a better one though asap.
Edit: My tank is at a constant 78-80 degrees. I feed him 2-3 Hikari pellets 2 times a day. And I test my water weekly with strips and his levels have been great for the past 2 months. (first month was the cycle so things were up and down a bit but he seemed to deal well)
Any help/suggestions are appreciated.