Hi all! I'm relatively new here, and I firstly want to thank everyone I've encountered so far, who have educated me on the proper way to keep my goldfish. I am planning to rehome my babies to a large tank or pond soon, but in the meantime I am looking ahead to what kind of fish I can keep in the 20gal tank that will be vacated. I do not want anything tropical as I prefer not to have to mess about with heaters. I don't care for Bettas so that's out. I have three young kids who like to watch lots of fish swim around, so if there's some kind that I could get a lot of (without overstocking of course) that would be ideal. Thanks in advance!