sad, I had something similar happen. The intake cover on the bottom of my powerhead fell off and my little pearlscale goldfish apparently went up to investigate.... When I turned it off and pulled him out one of his eyes was gone and blood had filled the gill/face area. I had to euthanize him.
I felt so bad! My other pearscale (his friend) died during my move from Wisconsin to Denver. Rest in Peace Lord & Lady Hui :-p