Feeding live vertibrates to other animals is illegal in the uk and for a very good reason, its cruel!!
I thought that people who kept animals, for whatever reason, did so because they simply love animals, life and every thing that it stands for. This mantis does not need to eat fish, mice, lizards, or any other vertibrate to remain healthy, but its not that that bothers me it is seeing a vertibrate with an advanced nervous system being slowly minced for some ones viewing pleasure. Yes i know they take them in the wild but that really isnt the point, they are not in the wild :shock: :evil: :x :evil:
I think you should check the laws in your country.
Edit: You could be banned from keeping any animals at all for 5-10 years in the UK if you were caught doing things like that.
Plus the fact some people feel strongly about it and dont what to see it.