peacock mantis tank question

[i have crabs]

Unless you have 1/4 glass dont worry about your mantis breaking your glass, its more of a myth than a problem, sure it could happen but i had one smash the glass plenty of times and ya it made me cringe but never any problem with a 3/8" tank,
Also watch what you feed him, i fed mine some goldfish feeders and he dropped dead, im thinking they were treated with copper,