Like I said, either the nicest schooling fish around or Satan straight from the depths of the underworld. In this case it happens to be satan. The siamese algae eaters, flying foxes, and oto cats all have a single solid stripe along their side. The chinese algae eaters have the vertical banding you're seeing on this fish.
My suggestion is to return him. These chinese algae eaters gain the reputation of sucking the eyeballs out of other fish and when they get bigger they just outright eat the other fish alive. They are one fish that do not belong in the hobby.