Okay I have a 10 gallon tank set up as the sick fish tank and in it right now is my mom's goldfish that has something wrong with him but I'm not sure what it is. I attached a photo of him its not very clear but what he looks like is: he is a solid orange fish but now he has black splotches on his dorsal fin and his sides, part of his tail is gone, and he's not eating. So any ideas on what he has.