Hello to all. I have two fantail goldfish in a 65 lt tank (20 gallons) for almost two years now with a HOB filter. Recently they had velvet and i did a treatment with esha exit for a few days. Now there are no signs of velvet but i keep checking them because i know it is very persitant. One of them grew a bulge on it's left side the last month, i cut back on feeding because at first i thought it was dropsy. Now he is better than last week. What could it be? Is it possible that it is fatty liver or some liver problem or internal parasites? I 've done big whater changes and bought a fishfood with more vitamins. The bulge is on the bigger fish (not the little white pimple), i couldn't take a better photo right now.