I have a goldfish that was was bread in my pond and moved to my 35 gallon goldfish tank to watch grow. There are 3 other gold fish around the same size as her in there. They will be moved to my pond once they outgrow the tank. This morning I noticed a new fungus like growth on its mouth and can’t seem to find anything like it. I went to freshwater specialist shop and they said it was some sort of bacterial infection. They recommended put it in a qt tank with a sponge filter, salt and melafix. It is currently in there. How often should I change the water? I am thinking every day do 50%. And then would I just have to add back half the amount of salt and melefix I added? All help is appreciate.