My 4-year-old wants a fish for Christmas, so I was just thinking "ok, so I get a bowl and a fish and some rocks, right?" But then my neighbor told me they need a filter to really thrive, or they just die in the bowl. I am scared to go into the pet store with this question as I feel like they will sell me the moon. But is that the consensus? A tank with a filter, and also use only distilled water and a special sponge to clean? I have never had a fish before.