I filmed a short clip in our fish shop, (not fish and chips).
It is excellent aquatics shop, one of the best, we are very lucky to live close.
Razorbacks are very quiet and they never come out in contrast to common musks. I watched them quite few times now. Are all razorbacks like that, very lay back? There are 3 or 4 Sternotherus carinatus in this tank, they always hiding in the corners. Here is the link if you are interested:
http://youtu.be/aEBz1wqb5gU