no there is absolutely no way to know 100% that the fish IS a pure labiatus or citrinellus just by looking at appearance. Now it would be possible to state 100% that it is NOT one or the other but it's kind small to make that determination. Also a bit small to try sexing and besides, the best way to sex them is by venting.
the guy i got it from told me its a red devil but after reading alot about mides and the red devil i found the same thing out der like the same fish hoping its a red devil lol