you need to figure out if it is lymph or ich. If it's ich you need to treat it right away. Lymph will not have an effect on the fish's behavior. He will act and eat normal (whatever that is for a clownfish). For lymph, a good diet with zoe or zoecon and no stress. It may heal on its own. Mine went away after 4 to 6 weeks. For ich, check the top of this forum for info on how to treat it and get started asap if you think it's ich. There are some photos on this board of clownfish with ich. It looks like you sprinkled salt all over the fish. Like specs. Lymphocyctis is a white greyish cotton looking bump that looks like you could scrape it off with your finger nail. It is like a wart to humans. My fish had a big clump on one fin and two other fins had a small speck. There was also a bump on his head, so 4 different spots on mine. Some describe it as cauliflower looking bumps.