Horrible bump/sore on fantail goldfish

[RockinRobin]

My fantailed goldfish developed two bumps under its scales, which rapidly grew over a few days and became red with a pus-filled, white center.

I have 3 goldfish in a well-established 38 gallon tank, with two Aquaclear 50 filters. My water tests today say:

NO3 20, No2 0, PH 6.5, KH 40, GH 180, NH3/NH4 0.

Every week, I do a 25% partial water change, treat water with API Stress Coat, Stress Zyme, and Aquarium salt as directed. I vacuum the gravel and rinse filters in the water I remove, and change filter inserts as directed.

I have treated with one 7-day round of Melafix for bacterial infections, and have been feeding Metro Med food. Then I did a partial water change, went to my pet store, and on their advice have started a second round of Melafix bacterial, and added treatment for Melafix fungus. One of the bumps disappeared, but the other has grown horribly (see the picture). What else can I do?

 

[jlk]

Hi! Welcome to AA!!! Lets start with a few questions. What are you using to test (liquid or strips)? What is your salinity/how much salt are you using and for how long? How long have you been feeding the MM? Do your fish's eyes normally appear bulged outwards or is this a new development? Do any of your other fish have symptoms? Do you have a quarantine tank? Do you also have Medigold?

We are going to come back to your ph/kh levels, water change schedule and the salt use once we are able to get your fish healthy because there are some concerns with this. For right now, I want you to do a 50% water change with temperature matched, properly conditioned water. Do not add anymore melafix/pimafix or anything else other than water conditioner dosed to your tank size. Once we have some more information, we can make further suggestions!