So what is the biggest tank needed for a tortoise. I started with a 29 gallon and then now I’m hearing 40 gallon. I just feel I wasted so much money but then again right not he is adjusting and not moving around and he will be inside not outside.+1 on getting pictures of the tortoise and also the enclosure. Please note that if this tortoise came from a chain pet store, it’s a wild caught adult and requires a minimum enclosure size of 8x4 feet. There is no tank big enough, and a 40 gallon really only works for a hatchling.