well, I certainly don't think going from a corner of the living room to getting an entire fish room /stufy constitutes crossing 'the limit'. 
she loves my fish and my hobby, she just doesn't like that it dominates a good portion of my life. I can understand that, and once the tank is finished and running, I think she will love it even more.
"Maybe in order to understand mankind, we have to look at the word itself: "Mankind". Basically, it's made up of two separate words - "mank" and "ind". What do these words mean ? It's a mystery, and that's why so is mankind." ~ Jack Handey