please help diagnose and cure my betta

[bettalicious]

Does anyone have advice on what is wrong with him and how to properly treat him?
I have a betta fish which I bought from a breeder when he was 10 weeks old. His fins were always short and started to grow. He is about 6 months old and all of a sudden he had a lump on his tail. I treated him with marycin two and revive. This seemed to help at first, but all of a sudden all his fins are disappearing.
I am treating him with marycin two but not sure if it is working. Originally, he was in a mini tank and I upgraded him to bernies betta cove 1 gallon, not using the filter. The problem started after he was in this tank. I put him in a different tank to see if that may have been the cause. He is in a tank by himself. I have 4 other bettas that all have their own tank and they seem to be fine.

 

[mom2reds]

how often are you doing water changes and due you use a heater?

 

[bettalicious]

originally every 2 weeks but lately every few days

 

[happygirl65]

How long has he been in the new tank and was it cycled before adding him?

 

[fisherman876]

I think it is fin rot

I am posting a couple of pictures of fin rot which I have found on net and are similar to yours

And I think my diagnosis is correct But I Can't suggest you the cure

 

[happygirl65]

It does look like fin rot but it could also be ammonia burns if the tank was not cycled....and a treatment of Maracyn would probably help a great deal if it is fin rot...but you may also want to find out what caused it so that it doesn't happen again.

Do you test your water parameters, or can you take your water and have it tested?
Ammonia, Nitrite, And Nitrate, these readings will tell you whether your tank is cycling or not.

In the mean time, the very best thing you can do is daily water changes, perhaps even two times a day and it might even resolve on it's own with just that.