Hi there I'm a new member here, but wanted to ask advice. We have a 3 year old goldfish who, over the past 6 months, has developed a huge lump on one side. I showed our vet pictures, and he said it looked like a tumour. The fish is swimming, eating, happily getting by. We have treated the water for fungus, and added in fish biotic tablets. Yet it still grows. Does anyone have any advice? Or do we just let nature take its course? Thank you!!