Odd behaviour with a boned object

I am making some animated fish using 3ds max. The first fish imported fine, animations work well etc. Second fish I made exactly the same way, imported it but when I add it to a scene to view it it rotates around following the first person camera. There are no scripts on the object, it is very weird, it almost turns inside out at one point. It depends on which direction I move around it.

It has something to do with the bones because if I set the root bone on the Skinned Mesh Renderer to 'none', it no longer does it, but then I lose the animations. Any ideas on this?

Edit: I found that by setting the Root Bone to 'none' actually fixed the problem, animations still run and the object stays in the correct rotation. But the first fish I made has the root bone set to the first bone and the problem doesn't happen. I would like to know why I get this behavior.