Turtles need calcium to build healthy shells and bones.
A cuttle fish bone in the tank will be nibbled on by most turtles and
supplies extra calcium. Get a new bone, when the old one get slimy!
There are also calcium supplements specially for reptiles.
* Vitamin D3
Synthesized in the turtle`s body using natural sunlight. A Reptile light with
the appropriate ratings for UVB is recommended,
or a supplement can be fed. There are supplements
available that contain Ca/D3.
Of course, the best way for your turtle get D3 is to get
unfiltered sunlight, and then it will synthesize the vitamin.
* The calcium to phosphor ratio of foods is important, as the more phosphor
there is in the food, the less calcium can be absorbed. 2:1 is a good ratio.
To find out more about this click here.