Hey guys, apologies if this is a noobie post but my goldfish has had this white pimple on it's head for about a month and a half now and it's not going away. It's swimming perfectly fine and has no other signs of illness. I've done more frequent water changes and doing stress coat/salt additives to cure but nothing happens. It's currently in a 50 gal tank with two other smaller goldfish and two plecos. What is the white spot? Is there anything I can do to remedy it? Thanks!