Betta fish tail turning white

[Dan117]

I have a betta and it’s tail started to disappear but I got that under control but now his tail is turning white and he has a couple of white spots on his body.

 

[EllRog]

I have a betta and it’s tail started to disappear but I got that under control but now his tail is turning white and he has a couple of white spots on his body. View attachment 126970View attachment 126971

I can't really see what you are referring to. What are the tank parameters? I'm assuming the fish is in a jar for the purpose of the picture?