It could also be a Harlequin shark, Labeo cyclorhynchus. The body shape is very similar. Also, RTBS tend to get very thick in the body,not just at the front, when at this size.
Its mouth doesent look like a RTBS as well, so ids say it was a Harlequin.
We've already established that it is a blue white finned rainbow shark new since 2004. Check out this link for pictures of of one:
http/aqualandpetsplus.com/Shark,%20Red-Tail.htm