cresteds will do fine fed the diet mix only. i use both the diet and crickets and offer peach babyfood as a treat. i feel that cresteds will grow quicker on crickets. a 15 or 20 gal. high tank is fine for one crested, if housing 2 adults look into a 29 or 30 high or larger. 2 females will do fine together but not always. i know some that keep more than one male in a setup, i personally don't do it.

vaughn