blister thing on my fish!

Question
I have a small pinky coloured fantail (male).
In the past weeks I've noticed a bite mark of some sort a blister thing on its right side, at first it was only a small sore until this past week it has grown very large and I am very worried. I was wondering what it was seeing I have already lost one fish and I am very close to my fish 'Bubbles'.Please HELP!

Answer
Tayla,                                                       I am checking the ? pool. I hope someone got back to you before I did. I hope bubbles is ok. I am assuming Bubbles is a goldfish. Since he has a fantail..... I would treat him with tetracycline 7 days remove carbon. Then A 25% water change and new carbon. If he isn't ok, and I am sorry if Bubbles isn't... you can keep your babies healthy with aquarium salt 1 tablespoon per 5 gallons..... it helps with stress and helps them release impurities from their system . I would also give them a frozen pea squeezed between your fingers once a week. It helps prevent swimbladder disease. Also ... get a veggie clip from your local petshop and cut slices of orange and cut the rind off half......they love it ... great for vitamin c. Good for their bones. I am pretty sure if you listen close they will be thanking you for it if their mouths aren't full. :)......I hope its not too late. Sometimes they get tumors and they can live with them for awhile, but try what I said . Good Luck,Tina