Often see folks make guesses of char species, like bull trout, for trout species like this cutty. Easiest way to remember is that "true" trout and salmon - genus Oncorhyncus (rainbows, cuttys, pacific salmon) and Salmo (brown trout, Atlantic salmon), have dark spots on a light background while char species, genus Salvelinus (bull trout, dollies, brook trout, lakers and arctic char) have light spots on a dark background. Remembering that, makes it easy to quickly determine if you have a fish from the trout/salmon group or a char species.
Ukee