Have you ever tried saltwater and/or tropical fish? How are they to take care of?
Never tried saltwater, but I imagine it's the same or more difficult as freshwater/tropical fish. I had Mollies, Swordtails, Platys, Neon Tetras, Fancy Guppies and a few Cory Catfish.
Most were livebearers, so I ended up with a bunch of baby fish (fry) and bought the 20 gallon to keep the adults in and the 10 was for babies. It was insane trying to keep those tanks clean and I spent a bunch of money in maintaining them (filters, chemicals, etc.)
I think fishtanks are terrific and will definitely have one again one day, but not until my girls are older and I have more time on my hands (and more money).