I've housed scorpions in normal 5-20 gallon tanks. Just be sure to get the type of lids that slide on and are secure. You can even put a lock on it. Depends on the type of scorpions you want to house. I've had Centruroides exilicauda housed this way (no lock though) with no problems. You just need to know the animal, how well it climbs, etc. Most pet scorps are not dangerous, if you are looking for hots (I would consider AZ bark scorpions mild compared to others) you'll want to take more precautions.