I’m brainstorming for what to do with my new 20 gallon. I have considered a split betta tank, I’ve always wanted a gold fancy goldfish, and now that I know the basics about fish keeping, I may attempt. So my question is, what kind of goldfish can you keep in a 20 gallon. And if none, what kind can you keep in a 29 gallon? I have some livebearers in my 29 gallon, which I stocked thinking it was only 20 gallons.