I would say, based on the definition of a chocolate Betta, that he is not. He is, though, a bi-color. Some refer to his type as "Mustard Gas (MG)." Hope the information helps.
According to the International Betta Congress, a chocolate should be non-iridescent and non-opaque.
According to the International Betta Congress, a chocolate should be non-iridescent and non-opaque.