Aquariums are fun. My mom has 2. One with the living dead betta (I think it's 2 gallons?) since bettas don't get along with other fish. The other is a 10 gallon and it's a little sad right now because there was a mean guppy who killed a few fish before dying himself. So there's just the survivor and the bottom cleaner. But she'll get more next time we're near the fish store.

For best results you have to test the water periodically and monitor the temperature and so it really does feel like caring for a pet. Plus they are fun to look at.