There are other substrates to use that are much safer than bran. Though many people do use wheatbran as a substrate, it does have risk of mold if it get damp (when dragons poo, the moisture from it is more than enough to dampen the wheat, not to mention provide breeding grounds for bacteria) Though spotcleaning can be done, it is very easy for the poo to get buried by the dragon running around if it goes while you are not around to scoop it out. Another risk with wheatbran is when it is wet, it can stick to the dragon's vent then dry into a hard crust which can cause irritation. Also bran can quickly harbor small bran mites, though not harmful to the dragon, means a swarming mass of tiny flies all over the cage and house.
Other substrates to use are non stick shelf liner (comes in many colors and patterns), plastic table cloth and reptile carpet.
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PHLdyPayne