Shark Pets or Mounts

Okay, so I have an Idea for a Pet or a Mount, which ever it becomes IF it is accepted

I was thinking of sharks

I mean what if we had a pet shark that flies behind us that changed between different species of sharks. Like how the dragons can change their colors.
It could even by an idea for a Mount, I mean how COOL would it be to ride a Great White or a Hammerhead shark?