When I had an apartment, in the lease it said fishtanks under X many gallons were fine. I think it was maybe 40g limit.
As to someone with a 2 page lease. I'm both a landlord and a renter. You want the lease to lay out all the details of what you can and cant do. Without proper legal documents, everything is fine until it is not and when push comes to shove, depending on state, you might get screwed on a silly issue. Although many states will side with the tenant before the landlord, it just depends...
I'm one of the few people that allows pets in their rental, however I do charge pet rent, and a pet deposit. If someone asked me about a fish tank, I would limit it to 29g on the main floors. basement would be whatever since under the flooring its concrete. I wouldnt charge a pet rent for the fish lol.
With the house we are currently renting, our lease had nothing in it about fish tanks. I setup our Edge tank, when the landlord first saw it, he looked at it the same way anyone else does, and kept walking.
Not in the lease so... =)
From my experience I had 2 55g tanks and a 40breeder in my apartment and one day I was bringing home a 10 from petco and the apartment manager saw me and told me I wasn't allowed to have aquariums I grinned and said i was actually a gift and was gonna be given away. Sure enough she was at my door the next day claiming she was doing inspection on he fire alarms and made me take down all my tanks or she would terminate my lease. Prior to this I've had my tanks for 2 years but I slipped up and got caught
Was it in the lease that you could not have fishtanks? If not, you could tell her she can't break the lease, if she tried you could sue her over it. Unexpected moving cost, time, and stress have a value. The lease is there to protect both of you. If it's not in there, it would be a straight forward court case. IMO she would have backed down as soon as you asked her where it said no fish, in the lease.