I hope you're not planning to keep one in an IQ5 as it is too small for a peacock mantis...
Just some things you need to consider before keeping one:
1. It has the potential of breaking glass (and as mentioned above, acrylic as well), so getting a tank with thicker walls should help.
2. There is certain risk in putting your bare hands in the tank, so precaution has to be taken. If you plan to add corals, do it before you add the mantis. I would stick a note beside the tank to serve as a reminder as well as to warn others about the danger.
3. Tank maintenance may be a problem, so a magnet cleaner would help.
4. Bio load may be high depending on what you feed, so be prepared for regular water changes.