I read that these cactuses are good for tortoises. I searched all our shops and got them but now I am confused because I have got 2 different Opuntia cactuses. Which is the real one that I can give to my Russian tortoises? The big or the small one? As they are not big, I will have to wait while they will grow bigger. But the question still is unclear - which one is the real opuntia cactus that can be eaten by toroises ! Thanks !