Do you have a fish that is behaving differently or looks different than it did the day before? Maybe its color is different. Maybe it’s hanging out in a place you’ve never seen it hang out before. Maybe it’s something, maybe it’s nothing. How do you determine if there is a problem or not?
That’s a tough question to answer, but the place to start is with elimination. You’ve heard “the process of elimination” before? Yep, start with trying to determine what the problem is NOT. As you eliminate possibilities, you’ll get closer to determining what, if anything, the problem might be.