My fish is quite happy in his environment. I don't know where you get 2ft of swimming space as their natural habits don't typical support that. As far as being bored I guarantee my fish gets more attention then yours do. I sit a play with him throughout the day, 8 hours a day 5 days a week. When I'm not around for those 2 days my cube mates often come over to say Hi.
He gets fed live food weekly and I stock the tank with small pond snails that he spends much of the day hunting for and eating. He is constantly active and entertained.
My recommendation comes from owning and watching my own fish. They use every inch of my 75g but I think a single (probably stunted) specimen would do ok in a 2ft aquarium if it was as beautifully planted as your bowl.
Possibly the most respected source of caresheets about atm and that suggests a minimum of 30 inches. Hes a fish, he doesn't need human companionship but he does need space to hunt, swim, nest and do everything else that comes naturally. From your photos he looks very pale, as the only occupant of the tank he should have strong dark colours to proclaim his health and dominance. He looks like one of my ladies when they have just lost a fight and are signalling their submission. Its a very clear sign of stress and has alerted me to problems in the past.