Google - I am studying the fathead Minot, We dissected a "cadaver" Minot since it had died.?

... Under examination I have noticed a red dot or two by the gills in the right side of the fish. Inside, the gills appear to be a bright red mush,with no resemblance of gills in any context. I began to believe it could be Chilodonella uncinata, but the tests came back negative. Any ideas on what could cause this in a fathead Minot?