It almost sounded to me like she was giving you the go ahead for a larger tank. Then She can have the fish in it that she likes. Win/Win.
I would choose the Wife over the tank any day. However, I would have a problem with anybody that put me in a position to make a decision like that. Now if she's the primary bread winner and your ****ing away her earning and working part time at walmart. Then she might as well kick your lazy arse out
The point is that there is always two sides to a story.