JuanTamad is correct, however why would you want to keep a 3' fish in a 2' wide tank....that is like keeping a 16" Oscar in a 55 Gallon...he can turn around, but he would obviously look cramped--its not the optimal arrangement. I have never seen a 3' Pbass in a tank, but DM and others are getting closer-I think DM's is a little over 2'. Keep em in a small tank for now and feed till bigger, then you should go with the 2' wide or bigger.
Chris