caixin isnt exactly the best, you need a better enclosure than a tub. A tub isnt going to work. soil or forest floor is perfectly ok, you can just remove the waste.
not exactly natural in my opinion but its so large already so it cant really get much better, but still a very nice tortoise. The shell isnt too bad.
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What is the enclosure? What do you feed it currently
well, my Radiated and Ploughshare tortoises never eat the poisonous plants even in their outdoor enclosure for example the Euphorbia. But they are wild animals so that may be why.