Bettas fin is shredded

Question
Hi Jaymie,

I have had my betta fish since May of this year, and he has always been very happy and active.  He gets excited when I enter the room and swims up and down the side of the glass very rapidly.  
Last month, he contracted some kind of disease in which his tail and top fin started to have a shredded appearance.  I did some research and thought it to be fin rot so I purchased BettaFix for him.  I administered the medicine like it said: half a teaspoon for 1-gallon for 7 days then a full water change.  I also got rid of the live plant, sun-dried my glass rocks and cleaned his bowl with hot water and let it air-dry.  I noticed that his tail and fin started getting better a few days after starting the treatment.  For a few weeks, he was fine -- his tail was still shredded but it didn't look like it was getting worse so I stopped the treatment.  
Then, just a few days ago, I noticed some white stuff on his fin and his tail has gotten much worse -- he actually has a huge rip down the middle of his tail now.  It looks like whatever got him before is back.  He lives alone and still acts the same.  He still swims up and down when he sees me and eats everything I feed him every time (Atison's Betta Food).  It looks like he has a harder time swimming now but it doesn't look like he has a bloated stomach.  I have noticed that he tends to lay near the bottom a lot more now and often times looks down at the rocks.  I try to keep his temperature around 78 degrees F and I make sure to change his water once a week.  I started giving him BettaFix again.  The edges of his tail are black now but white stuff on his top fin is gone.  I'm on day 5 of that treatment but I don't know if it's helping or if I'm even targeting the right thing.
Do you know what he might have and what I need to do to help him get better?  He's such a great fish and I feel so bad for him!

Thank you,
Kay

Answer
Kay,

Bettafix is not a good product, and I would not use it any more. Using this product might be contributing to why he doesn't swim much. If you are treating for fin rot,  I would give him salt water baths.

*direction below*

Salt water bath (dip): Get a container that can hold 1 gallon of water the same temp as the tank water. Add 1 teaspoon of aquarium salt that has been dissolved before adding your fish to that water. If you don't dissolve it first it can burn your fish. Let him swim in this water for 15 minutes, watching him closely the entire time he is in there. I want you to watch him in case he starts to have a problem, you can remove him from the salt water immediately. I would do this 2 times a day, but never in the same water. Always make fresh salt water every time you put him in. Some people say if you add aquarium salt to the tank, it helps prevent this problem. I personally do not add salt to my tanks.

I would replace the Bettafix with Marcyn-Two as soon as you can. If you have a filter, remember to remove the charcoal/carbon. If you don't, the filter remove all the medicine in the water before it gets a chance to work.