The truth of the matter is, if you're tight on cash, you shouldn't be buying another animal. Save your money and when you can truly afford the appropriate set up, buy the stuff that you need and THEN purchase a new animal. There's no need to rush things. And to answer your original question, fat tails and leopard have entirely different needs. So, no...they should not be housed together. Take the time that you're saving up some money to do some research as to the requirements of fat tails as well.