I am asking this question for a friend of mine who seems to have fallen in love with oscars. The only problem is that we are both students and don't have very much disposable income to spend on fish. We have gone to the LFS several times and have concluded that a tank over 50 gallons is too much money, but he is still intent on getting an oscar. I have been trying to tell him that an oscar probably won't fit in the tank, but he wants to get one anyways. The only plus is that he only wants to get one. The tank that he has right now (and is planing to keep the oscar in) messures 40"x12"x20" (not sure how many gallons that is). I have told him that 12" deep will not be enough but I need some other opinions. Is 12" deep ok? Am I wrong? Thanks for your time.