Tub size is really a personal preference based on how you decide to set it up. For a hatchling it is pretty traditional to go with a 6 qt tub. I use this for most hatchlings, and just have a water bowl and no hide. You can start a hatchling in an adult sized 28-41 qt tub but likely you would need to add some hides and stuff to clutter up the tub to allow the hatchling to feel secure.