Hello all , I’m new to your group . Have a 75 gallon tank for 4 years now , mostly underpopulated with fish . My question relates to my silver dollars. They are fairly large 3 1/2 inches long. The one has a white oval elongated strip on its left side. Looks like an injury from banging into something .Chemistry is always been good , tank is looked after well. I’ve attached some pictures of the injury or health issue . what are your thoughts about this? Thank you so much for your anticipated response. Rob