Fish Tumor

On Tuesday, I looked into the 23 gallon aquarium that we have and I noticed a disturbing thing. This fancy goldfish that you see here had developed what I believe, after extensive research, to be a tumor. It looks like something is trying to erupt from the side of the fish just beside its right gills. At the tip of the protuberance, is a white tip that looks like a zit ready to be popped. Due to this ailment, I had to move the fish out of his aquarium into a vase that we had handy. It was the best I could do on short notice. Hopefully, he'll be okay. There doesn't seem to be much I can do right now. I'm just going to keep him quarantined and his bowl clean.