What exactly are fantail goldfish, as in, what set of requirements do they have? I've seen that common goldfish need more space in general than fancy goldfish do. I'm assuming that fantails are classified as fancy goldfish, but I'm not 100% sure. Anyway, the reason I'm asking this is because I have two in a 29 gallon tank with a filter rated for a tank of 30-50 gallons. They're the only inhabitants, and I'm wondering if this is an adequate setup. Also, how fast do fantails grow?