Yes. Tortoises housed indoors need appropriate UVB exposure. UVB allows the body to produce vitamin D3 and use calcium normally, which is critical to healthy bone and shell development.
Does sunlight through a window count?
No. Glass and plastic filter useful UVB. Outdoor natural sunlight can provide UVB when weather and the enclosure are safe, but indoor tortoises need an appropriate reptile UVB source.
What strength UVB does my tortoise need?
That depends on the species and the lamp/setup. Mediterranean tortoises are commonly provided high-output UVB, while placement depends on the lamp, fixture, enclosure and manufacturer instructions. Do not choose distance by a universal number.
Does UVB replace heat?
No. Tortoises also need an appropriate thermal gradient and basking area. UVB and heat are separate parts of the setup even when a particular lamp provides both.
Browse Tortoises & Turtles for UVB, heating and habitat supplies.