A person whose entire life revolves around one thing and who is perfectly happy remaining
ignorant of real life and the outside world.
Like how a fish is perfectly happy inside of their
bowl, not even caring that there is an entire
ocean out there.
Jeremy is such a fish. All he does is go to the
gym, talk about the
gym, eat at the gym, and think about the gym. Does he do anything else besides the gym? No, because he's a fish.