There's a creek behind our building at work and there were a number of what look like rainbow trout to me. This one was maybe six inches long. It and another of the same length as well as some fingerlings were caught in a shallow area, probably due to the recent rain and changing water.
I'm not sure what's on it's head. It looks almost like a parasite, but the marks are very regular. Maybe it's some stress reaction to the very shallow water.