Hi tracey, recognize you from HD forum here ;-)

The answer to your question all depends on what your future Landlord will permit. I'm LL of houses, not apartments, but the one hindrance I see is potential water damage. I know this because I inherited a large aquarium from certain little people in my family whom I adore and cannot say "No" to (and they know this and use it to full advantage when they can. ;) So less than a month after I get the aquarium I wake up to the sound of water running. Thinking it's DH, I nod off to sleep again. Only suddenly it dawns on me it's the middle of the night, DH is snoring and that's the sound of a lot of water. Bolt out of bed, run to the source, sure enough, darn thing sprung a leak. Where the glass meets at a seam. And a big pool of water was spreading rapidly toward our furniture 5' away. It was like something out of the three stooges. I called DH to help me, I'm frantically mopping up water with towels, mops, you name it. Meanwhile DH is scooping up fish into a bucket and really not happy. All of this occurred on brand new flooring. Thankfully, we had picked a commercial grade hardwood look-alike with a rubber bottom side for moisture barrier/cushion, since it was being installed in our lower level over concrete. Seams were sealed tight, but DH grabbed his shop vac and hit all the seams just to be safe. It was a nightmare.

So, I get that you like your fish. ;) And I'd definitely make that one of your top questions when you're checking places. Imagine at ten yrs they're good size. Is there any way they can be temporarily housed in a large fish bowl - or very small aquarium (less gallons) if a pump is necessary? The lower gallons the better it will sound to potential LLs or Prop Mgrs. ;-)

If you're negotiating with a landlord who has reservations about it, consider adding a cheap rider to your renter's insurance to cover any potential water damage (if it's not already covered in the basic policy).