Its NOT an atlantic blue, but without a better pic you won't get a good answer.
ok.
And you know this because?
The shape of the anal fin (more rounded in an atlantic blue at that age), the color of the scalpel, the yellow edge to the dorsal fin (Atlantic blues, normally have a blue edge even when yellow), the shape of the tail (seems more emarginate shaped, than truncated (like an atlantic blue)), shape of the body (more elongated than the more rounded shape of an atlantic blue at that age), and then the lack of stripes (usually the stripes are pretty obvious in an atlantic blue tang, both in the fins and on the body, the pic isn't the best, but it looks way to uniform in color).
Hope that helps.
The shape of the anal fin (more rounded in an atlantic blue at that age), the color of the scalpel, the yellow edge to the dorsal fin (Atlantic blues, normally have a blue edge even when yellow), the shape of the tail (seems more emarginate shaped, than truncated (like an atlantic blue)), shape of the body (more elongated than the more rounded shape of an atlantic blue at that age), and then the lack of stripes (usually the stripes are pretty obvious in an atlantic blue tang, both in the fins and on the body, the pic isn't the best, but it looks way to uniform in color).
Hope that helps.