I'm afraid that I started this near myth about stomatopods and glass tanks. In the early 70's, I had a large (18 cm) Odontodactylus scyllarus break the face plate of one of the old "Instant Ocean" marine tanks. That glass was thick double-glazing. I mentioned this in a few popular pieces about stomatopods and the story has been around ever since. Large smashers such as Odontodactylus scyllarus and Hemisquilla ensigera can break glass, but they USUALLY don't. Any thing under 4 inches I would not hesitate to keep in a normal glass tank. Still, I wouldn't tease the animal and try to get it to strike at your finger through the glass.
Roy