Since I changed his water yesterday with only less salt and melafix he has been doing fine but this tail does not seem to get any better or worst, he is also not swimming on his sides anymore but just in case I will start feeding him peas. H eis acting preety normal, the only thing that is out of the norm is his tail. But he does seem to be getting a little better.
thanks for the advice
Karla,
What size tank do you keep BM in and what other fish?
The number one cause of goldfish health problems are related to water quality issues. If you keep their water quality in good shape, they will usually stay healthier but if their water is regularly getting too dirty, high nitrates (or ammonia/nitrites), etc., they will be more sickly.
You should have at least 30G of water volume for each fancy goldfish and even that would need to be filtered well and partial water changes done at least weekly to keep them healthy long term. Vacuuming the gravel at least weekly and doing filter cleaning at least weekly is also needed.
Here's my Fancy Goldfish Care Sheet since I haven't found any other Goldfish Care Sheets that are really that good.
http://goldlenny.blogspot.com/2007/03/goldfish-care-sheet-fancy-goldfish.html
Depending on how bad the fin got, it could take a couple of weeks to grow back. If the fin rotted all the way down to the peduncle (the flesh at the base of the fin) then that area may not grow back.
Keep up the PWC's (partial water changes), DAILY if possible, and keep treating with Melafix.
The swimbladder issue is likely due to bacterial infection in the digestive tract which is causing swelling of one or more organs and then those organs put pressure on one of the two swim bladders or on the tubes/valves controlling the swim bladder and then the fish can't regulate the swim bladders properly so they go lopsided.
Feed green pea *meat* (pinch the green peas to and discard the skin) daily as they love it and it's kind of a laxative for them so it will flush out any constipation issues that can also cause swim bladder issues.