Yeah its important to provide calcium-rich food for them. Cuttlefish bone is a must. Also boil an egg, let it cool down and see if they eat it. some will. Also petit filous, but natural plain yoghurt is also good if not better. Mushrooms for vitamin D, they will probably choose to eat other food first but they will eat a bit of the mushroom. Also have you tried the vitakraft mineral block? thats a must too always have one in your cage for them