Question

How do you get a Deino that knows Ice Fang when in fact no Dragon type knows it?

Answer 1

Breed it with a Arbok or Gyrados that knows Ice Fang and is a male.
Arbok learns it at level 1, so give it to the move relearner.
Gyrados learns it at level 32.

Deino egg moves page here

Answer 2

you need to breed a deino that has a gyrados or arbok that knows ice fang as a father